View source for Cardiac arrest

{{Short description|Sudden stop in effective blood flow due to the failure of the heart to contract effectively}}
{{Other uses}}
{{Infobox medical condition (new)
| name            = Cardiac arrest
| image           = US Navy 040421-N-8090G-001 Hospital Corpsman 3rd Class Flowers administers chest compressions to a simulated cardiac arrest victim.jpg
| caption         = [[Cardiopulmonary resuscitation|CPR]] being administered during a simulation of cardiac arrest.
| synonyms        = Cardiopulmonary arrest, circulatory arrest, sudden cardiac arrest (SCA), sudden cardiac death (SCD)<ref name=Fie2009/>
| field           = [[Cardiology]], [[emergency medicine]]
| symptoms        = [[unconsciousness|Loss of consciousness]], [[respiratory arrest|abnormal or no breathing]]<ref name=Fie2009/><ref name=NIH2016Sign/>
| complications   = 
| onset           = Older age<ref name=NIH2016Risk/>
| duration        = 
| causes          = [[Coronary artery disease]], [[congenital heart defect]], major [[bleeding|blood loss]], lack of oxygen, [[hypokalemia|very low potassium]], [[heart failure]]<ref name=NIH2016Ca/>
| risks           = 
| diagnosis       = Finding no pulse<ref name=Fie2009/>
| differential    = 
| prevention      = Not smoking, physical activity, maintaining a healthy weight, healthy eating<ref name=NIH2016Pre/>
| treatment       = [[Cardiopulmonary resuscitation]] (CPR), [[defibrillation]]<ref name=NIH2016Tx/>
| medication      = 
| prognosis       = Survival rate ~ 10% (outside of hospital) 25% (in hospital)<ref name=Adam2012/><ref name=JAMA2019>{{cite journal |last1=Andersen |first1=LW |last2=Holmberg |first2=MJ |last3=Berg |first3=KM |last4=Donnino |first4=MW |last5=Granfeldt |first5=A |title=In-Hospital Cardiac Arrest: A Review. |journal=JAMA |date=26 March 2019 |volume=321 |issue=12 |pages=1200–1210 |doi=10.1001/jama.2019.1696 |pmid=30912843|pmc=6482460 }}</ref>
| frequency       = 13 per 10,000 people per year (outside hospital in the US)<ref name=AHA2015Part4/>
| deaths          = > 425,000 per year (U.S.)<ref>{{cite journal |last1=Meaney |first1=PA |last2=Bobrow |first2=BJ |last3=Mancini |first3=ME |last4=Christenson |first4=J |last5=de Caen |first5=AR |last6=Bhanji |first6=F |last7=Abella |first7=BS |last8=Kleinman |first8=ME |last9=Edelson |first9=DP |last10=Berg |first10=RA |last11=Aufderheide |first11=TP |last12=Menon |first12=V |last13=Leary |first13=M |last14=CPR Quality Summit Investigators, the American Heart Association Emergency Cardiovascular Care Committee, and the Council on Cardiopulmonary, Critical Care, Perioperative and |first14=Resuscitation. |title=Cardiopulmonary resuscitation quality: [corrected] improving cardiac resuscitation outcomes both inside and outside the hospital: a consensus statement from the American Heart Association. |journal=Circulation |date=23 July 2013 |volume=128 |issue=4 |pages=417–35 |doi=10.1161/CIR.0b013e31829d8654 |pmid=23801105|doi-access=free }}</ref>
}}
<!-- Definition and symptoms -->
'''Cardiac arrest''' is a sudden loss of [[circulatory system|blood flow]] resulting from the failure of the [[heart]] to pump effectively.<ref name=NIH2016What/> Signs include [[unconsciousness|loss of consciousness]] and [[respiratory arrest|abnormal or absent breathing]].<ref name=Fie2009>{{cite book|last1=Field|first1=John M. | name-list-style = vanc |title=The Textbook of Emergency Cardiovascular Care and CPR|date=2009|publisher=Lippincott Williams & Wilkins|isbn=9780781788991|page=11|url=https://books.google.com/books?id=JaOoXdSlT9sC&pg=PA11|language=en|url-status=live|archive-url=https://web.archive.org/web/20170905133735/https://books.google.com/books?id=JaOoXdSlT9sC&pg=PA11|archive-date=2017-09-05}}</ref><ref name=NIH2016Sign/> Some individuals may experience [[chest pain]], [[shortness of breath]], or [[nausea]] before cardiac arrest.<ref name=NIH2016Sign>{{cite web|title=What Are the Signs and Symptoms of Sudden Cardiac Arrest?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/scda/signs|website=NHLBI|access-date=16 August 2016|date=June 22, 2016|url-status=live|archive-url=https://web.archive.org/web/20160827190624/http://www.nhlbi.nih.gov/health/health-topics/topics/scda/signs|archive-date=27 August 2016}}</ref> If not treated within minutes, it typically leads to [[death]].<ref name=NIH2016What>{{cite web|title=What Is Sudden Cardiac Arrest?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/scda|website=NHLBI|access-date=16 August 2016|date=June 22, 2016|url-status=live|archive-url=https://web.archive.org/web/20160728031608/http://www.nhlbi.nih.gov/health/health-topics/topics/scda|archive-date=28 July 2016}}</ref>

<!-- Cause and diagnosis -->
The most common cause of cardiac arrest is [[coronary artery disease]].<ref name=NIH2016Ca/> Less common causes include major [[bleeding|blood loss]], [[Hypoxia (medical)|lack of oxygen]], [[hypokalemia|very low potassium]], [[heart failure]], and [[Anaerobic exercise|intense physical exercise]].<ref name=NIH2016Ca/> A number of inherited disorders may also increase the risk including [[long QT syndrome]].<ref name=NIH2016Ca/> The initial heart rhythm is most often [[ventricular fibrillation]].<ref name=NIH2016Ca>{{cite web|title=What Causes Sudden Cardiac Arrest?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/scda/causes|website=NHLBI|access-date=16 August 2016|date=June 22, 2016|url-status=live|archive-url=https://web.archive.org/web/20160728042233/http://www.nhlbi.nih.gov/health/health-topics/topics/scda/causes|archive-date=28 July 2016}}</ref> The diagnosis is confirmed by finding no [[pulse]].<ref name=Fie2009/> While a cardiac arrest may be caused by [[myocardial infarction|heart attack]] or heart failure, these are not the same.<ref name=NIH2016What/>

<!-- Treatment and prognosis -->
Prevention includes not smoking, physical activity, and maintaining a healthy weight.<ref name=NIH2016Pre/> Treatment for cardiac arrest includes immediate [[cardiopulmonary resuscitation]] (CPR) and, if a [[shockable rhythm]] is present, [[defibrillation]].<ref name=NIH2016Tx>{{cite web|title=How Is Sudden Cardiac Arrest Treated?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/scda/treatment|website=NHLBI|access-date=16 August 2016|date=June 22, 2016|url-status=live|archive-url=https://web.archive.org/web/20160827184130/http://www.nhlbi.nih.gov/health/health-topics/topics/scda/treatment|archive-date=27 August 2016}}</ref> Among those who survive, [[targeted temperature management]] may improve outcomes.<ref name=":5"/><ref name=Arr2016>{{cite journal | vauthors = Arrich J, Holzer M, Havel C, Müllner M, Herkner H | title = Hypothermia for neuroprotection in adults after cardiopulmonary resuscitation | journal = The Cochrane Database of Systematic Reviews | volume = 2 | pages = CD004128 | date = February 2016 | pmid = 26878327 | doi = 10.1002/14651858.CD004128.pub4 | pmc = 6516972 }}</ref> An [[implantable cardiac defibrillator]] may be placed to reduce the chance of death from recurrence.<ref name=NIH2016Pre>{{cite web|title=How Can Death Due to Sudden Cardiac Arrest Be Prevented?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/scda/prevention|website=NHLBI|access-date=16 August 2016|date=June 22, 2016|url-status=live|archive-url=https://web.archive.org/web/20160827200432/http://www.nhlbi.nih.gov/health/health-topics/topics/scda/prevention|archive-date=27 August 2016}}</ref>

<!-- Epidemiology and history -->
In the [[United States]], approximately 535,000 cases occur a year.<ref name=AHA2015Part4/> About 13 per 10,000 people (326,000 or 61%) experience cardiac arrest outside of a hospital setting, while 209,000 (39%) occur within a hospital.<ref name=AHA2015Part4>{{cite journal | vauthors = Kronick SL, Kurz MC, Lin S, Edelson DP, Berg RA, Billi JE, Cabanas JG, Cone DC, Diercks DB, Foster JJ, Meeks RA, Travers AH, Welsford M | title = Part 4: Systems of Care and Continuous Quality Improvement: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 132 | issue = 18 Suppl 2 | pages = S397-413 | date = November 2015 | pmid = 26472992 | doi = 10.1161/cir.0000000000000258 | s2cid = 10073267 | doi-access = free }}</ref> Cardiac arrest becomes more common with age.<ref name=NIH2016Risk/> It affects males more often than females.<ref name=NIH2016Risk>{{cite web|title=Who Is at Risk for Sudden Cardiac Arrest?|url=http://www.nhlbi.nih.gov/health/health-topics/topics/scda/atrisk|website=NHLBI|access-date=16 August 2016|date=June 22, 2016|url-status=live|archive-url=https://web.archive.org/web/20160823231651/http://www.nhlbi.nih.gov/health/health-topics/topics/scda/atrisk|archive-date=23 August 2016}}</ref> The percentage of people who survive out of hospital cardiac arrest with treatment by emergency medical services is about 8%.<ref name=Adam2012/> Many who survive have significant [[disability]].<ref name=Adam2012/> However, many American television programs have portrayed unrealistically high survival rates of 67%.<ref name=Adam2012>{{cite book|last1=Adams|first1=James G.| name-list-style = vanc |title=Emergency Medicine: Clinical Essentials (Expert Consult – Online)|date=2012|publisher=Elsevier Health Sciences|isbn=978-1455733941|page=1771|url=https://books.google.com/books?id=rpoH-KYE93IC&pg=PA1771|language=en|url-status=live|archive-url=https://web.archive.org/web/20170905133735/https://books.google.com/books?id=rpoH-KYE93IC&pg=PA1771|archive-date=2017-09-05}}</ref>

==Signs and symptoms==
Cardiac arrest is not preceded by any warning symptoms in approximately 50 percent of people.<ref name=":2">{{cite book|title=Braunwald's heart disease : a textbook of cardiovascular medicine | publisher=Saunders|others=Mann, Douglas L.; Zipes, Douglas P.; Libby, Peter; Bonow, Robert O.; Braunwald, Eugene|year=2015|isbn=9781455751341|editor-last=Myerburg|editor-first=Robert J. | name-list-style = vanc |edition=Tenth|location=Philadelphia, PA|pages=821–860|chapter=Cardiac Arrest and Sudden Cardiac Death|oclc=890409638}}</ref> For those who do experience symptoms, they will be non-specific, such as new or worsening [[chest pain]], [[fatigue (medical)|fatigue]], [[syncope (medicine)|blackout]]s, [[dizziness]], [[shortness of breath]], [[weakness]] and [[vomiting]].<ref>{{cite web|url=https://www.nhlbi.nih.gov/health/health-topics/topics/scda/signs|title=What Are the Signs and Symptoms of Sudden Cardiac Arrest?|date=1 April 2011|publisher=National Heart, Lung and Blood Institute|archive-url=https://web.archive.org/web/20150621171145/https://www.nhlbi.nih.gov/health/health-topics/topics/scda/signs|archive-date=21 June 2015|url-status=live|access-date=2015-06-21}}</ref><ref>{{Citation|last1=Johnson|first1=Ken|title=Chest Pain|date=2019|url=http://www.ncbi.nlm.nih.gov/books/NBK470557/|work=StatPearls|publisher=StatPearls Publishing|pmid=29262011|access-date=2019-11-05|last2=Ghassemzadeh|first2=Sassan}}</ref> When cardiac arrest occurs, the most obvious sign of its occurrence will be the lack of a palpable [[pulse]] in the victim. Also, as a result of loss of [[cerebral circulation|cerebral perfusion]] (blood flow to the [[human brain|brain]]), the victim will rapidly lose [[unconsciousness|consciousness]] and will stop breathing. The main criterion for diagnosing a cardiac arrest, as opposed to [[respiratory arrest]], which shares many of the same features, is lack of [[Circulatory system|circulation]]; however, there are a number of ways of determining this. [[Near-death experience]]s are reported by 10 to 20 percent of people who survived cardiac arrest.<ref>{{cite journal | vauthors = Parnia S, Spearpoint K, Fenwick PB | title = Near death experiences, cognitive function and psychological outcomes of surviving cardiac arrest | journal = Resuscitation | volume = 74 | issue = 2 | pages = 215–21 | date = August 2007 | pmid = 17416449 | doi = 10.1016/j.resuscitation.2007.01.020 }}</ref>

Certain types of prompt intervention can often reverse a cardiac arrest, but without such intervention, death is all but certain.<ref name="Harrison2">{{cite book|title=Harrison's principles of internal medicine| vauthors = Jameson JL, Kasper DL, Harrison TR, Braunwald E, Fauci AS, Hauser SL, Longo DL |publisher=McGraw-Hill Medical Publishing Division|year=2005|isbn=978-0-07-140235-4|location=New York}}</ref> In certain cases, cardiac arrest is an anticipated outcome of a serious illness where death is expected.<ref>{{cite web|url=http://www.mountsinai.org/patient-care/health-library/diseases-and-conditions/coronary-artery-disease|title=Mount Sinai – Cardiac arrest|archive-url=https://web.archive.org/web/20120515004036/http://www.mountsinai.org/patient-care/health-library/diseases-and-conditions/coronary-artery-disease|archive-date=2012-05-15|url-status=live}}</ref>

==Causes==
[[File:2018 Conduction System of Heart.jpg|thumb|330x330px|Conduction system of heart]]

Sudden cardiac arrest (SCA) and sudden cardiac death (SCD) occur when the heart abruptly begins to beat in an abnormal or irregular rhythm ([[Heart arrhythmia|arrhythmia]]).<ref name=":6" /> Without organized electrical activity in the heart muscle, there is no consistent contraction of the [[ventricle (heart)|ventricle]]s, which results in the heart's inability to generate an adequate [[cardiac output]] (forward pumping of blood from heart to rest of the body).<ref name=UTD2016>{{cite web|url=https://www.uptodate.com/contents/pathophysiology-and-etiology-of-sudden-cardiac-arrest?source=see_link#H5|title=Pathophysiology and etiology of sudden cardiac arrest|last=Podrid|first=Philip J| name-list-style = vanc |date=2016-08-22|website=www.uptodate.com|access-date=2017-12-03}}</ref> There are many different types of [[Heart arrhythmia|arrhythmias]], but the ones most frequently recorded in SCA and SCD are [[ventricular tachycardia]] (VT) or [[ventricular fibrillation]] (VF).<ref>{{cite journal | vauthors = Zipes DP, Camm AJ, Borggrefe M, Buxton AE, Chaitman B, Fromer M, Gregoratos G, Klein G, Moss AJ, Myerburg RJ, Priori SG, Quinones MA, Roden DM, Silka MJ, Tracy C, Smith SC, Jacobs AK, Adams CD, Antman EM, Anderson JL, Hunt SA, Halperin JL, Nishimura R, Ornato JP, Page RL, Riegel B, Blanc JJ, Budaj A, Dean V, Deckers JW, Despres C, Dickstein K, Lekakis J, McGregor K, Metra M, Morais J, Osterspey A, Tamargo JL, Zamorano JL | title = ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (writing committee to develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society | journal = Circulation | volume = 114 | issue = 10 | pages = e385-484 | date = September 2006 | pmid = 16935995 | doi = 10.1161/CIRCULATIONAHA.106.178233 | author-link9 = Arthur J. Moss | doi-access = free }}</ref> Less common causes of dysrhythmias in cardiac arrest include [[pulseless electrical activity]] (PEA) or [[asystole]].<ref name=":6" /> Such rhythms are seen when there is prolonged cardiac arrest, progression of ventricular fibrillation, or due to efforts such as defibrillation to resuscitate the person.<ref name=":6" />

Sudden cardiac arrest can result from cardiac and non-cardiac causes including the following:

=== Coronary artery disease ===
[[Coronary artery disease]] (CAD), also known as [[ischemic heart disease]], is responsible for 62 to 70 percent of all SCDs.<ref name=":0">{{cite journal | title = State-specific mortality from sudden cardiac death—United States, 1999 | journal = MMWR. Morbidity and Mortality Weekly Report | volume = 51 | issue = 6 | pages = 123–6 | date = February 2002 | pmid = 11898927| author1 = Centers for Disease Control Prevention (CDC) }}</ref><ref name=":1">{{cite journal | vauthors = Zheng ZJ, Croft JB, Giles WH, Mensah GA | title = Sudden cardiac death in the United States, 1989 to 1998 | journal = Circulation | volume = 104 | issue = 18 | pages = 2158–63 | date = October 2001 | pmid = 11684624 | doi = 10.1161/hc4301.098254 | doi-access = free }}</ref> CAD is a much less frequent cause of SCD in people under the age of 40.<ref name=":0" />

Cases have shown that the most common finding at postmortem examination of sudden cardiac death (SCD) is chronic high-grade [[stenosis]] of at least one segment of a major coronary artery, the arteries that supply the heart muscle with its blood supply.<ref>{{cite book |url=https://books.google.com/books?id=1WifwPEsKQMC&pg=PA460 |title=Atherothrombosis and Coronary Artery Disease |last1=Fuster |first1=Valentin |last2=Topol |first2=Eric J. |last3=Nabel |first3=Elizabeth G. | name-list-style = vanc |date=2005|publisher=Lippincott Williams & Wilkins|isbn=9780781735834|language=en|archive-url=https://web.archive.org/web/20160603002043/https://books.google.com/books?id=1WifwPEsKQMC&pg=PA460&lpg=PA460|archive-date=2016-06-03|url-status=live}}</ref>

===Structural heart disease===
Structural heart diseases not related to CAD account for 10% of all SCDs.<ref name=UTD2016/><ref name=":1" /> Examples of these include:  [[cardiomyopathy|cardiomyopathies]] ([[hypertrophic cardiomyopathy|hypertrophic]], [[dilated cardiomyopathy|dilated]], or [[Arrhythmogenic cardiomyopathy|arrythmogenic]]), [[Cardiac arrhythmia|cardiac rhythm disturbances]], congenital [[Coronary artery anomaly|coronary artery anomalies]], [[myocarditis]], [[hypertensive heart disease]],<ref name="Circ012">{{cite journal | vauthors = Zheng ZJ, Croft JB, Giles WH, Mensah GA | title = Sudden cardiac death in the United States, 1989 to 1998 | journal = Circulation | volume = 104 | issue = 18 | pages = 2158–63 | date = October 2001 | pmid = 11684624 | doi = 10.1161/hc4301.098254 | doi-access = free }}</ref> and [[congestive heart failure]].<ref name="AHJ982">{{cite journal | vauthors = Kannel WB, Wilson PW, D'Agostino RB, Cobb J | title = Sudden coronary death in women | journal = American Heart Journal | volume = 136 | issue = 2 | pages = 205–12 | date = August 1998 | pmid = 9704680 | doi = 10.1053/hj.1998.v136.90226 }}</ref>

[[Left ventricular hypertrophy]] is thought to be a leading cause of SCD in the adult population.<ref>{{cite journal | vauthors = Stevens SM, Reinier K, Chugh SS | title = Increased left ventricular mass as a predictor of sudden cardiac death: is it time to put it to the test? | journal = Circulation: Arrhythmia and Electrophysiology | volume = 6 | issue = 1 | pages = 212–7 | date = February 2013 | pmid = 23424223 | pmc = 3596001 | doi = 10.1161/CIRCEP.112.974931 }}</ref><ref name=":6" /> This is most commonly the result of longstanding [[Hypertension|high blood pressure]] which has caused secondary damage to the wall of the main pumping chamber of the heart, the [[Ventricle (heart)#Pumping volume|left ventricle]].<ref>{{cite journal | vauthors = Katholi RE, Couri DM | title = Left ventricular hypertrophy: major risk factor in patients with hypertension: update and practical clinical applications | journal = International Journal of Hypertension | volume = 2011 | pages = 495349 | year = 2011 | pmid = 21755036 | pmc = 3132610 | doi = 10.4061/2011/495349 }}</ref>

A 1999 review of SCDs in the United States found that this accounted for over 30% of SCDs for those under 30 years. A study of military recruits age 18-35 found that this accounted for over 40% of SCDs.<ref name=":0" /><ref name=":1" />

Congestive heart failure increases the risk of SCD fivefold.<ref name="AHJ982" />

=== Inherited arrhythmia syndromes ===
Arrhythmias that are not due to structural heart disease account for 5 to 10% of sudden cardiac arrests.<ref>{{cite journal | vauthors = Chugh SS, Kelly KL, Titus JL | title = Sudden cardiac death with apparently normal heart | journal = Circulation | volume = 102 | issue = 6 | pages = 649–54 | date = August 2000 | pmid = 10931805 | doi = 10.1161/01.cir.102.6.649 | doi-access = free }}</ref><ref>{{cite journal | title = Survivors of out-of-hospital cardiac arrest with apparently normal heart. Need for definition and standardized clinical evaluation. Consensus Statement of the Joint Steering Committees of the Unexplained Cardiac Arrest Registry of Europe and of the Idiopathic Ventricular Fibrillation Registry of the United States | journal = Circulation | volume = 95 | issue = 1 | pages = 265–72 | date = January 1997 | pmid = 8994445 | doi = 10.1161/01.cir.95.1.265 }}</ref><ref name=":4">{{cite journal | vauthors = Drory Y, Turetz Y, Hiss Y, Lev B, Fisman EZ, Pines A, Kramer MR | title = Sudden unexpected death in persons less than 40 years of age | journal = The American Journal of Cardiology | volume = 68 | issue = 13 | pages = 1388–92 | date = November 1991 | pmid = 1951130 | doi = 10.1016/0002-9149(91)90251-f }}</ref> These are frequently caused by [[genetic disorder]]s that lead to abnormal heart rhythms.<ref name=":6" /> The genetic [[mutation]]s often affect specialised proteins known as [[ion channel]]s that conduct [[Ion|electrically charged particles]] across the [[cell membrane]], and this group of conditions are therefore often referred to as [[Channelopathy|channelopathies]]. Examples of these inherited arrhythmia syndromes include [[Long QT syndrome]], [[Brugada Syndrome]], [[Catecholaminergic polymorphic ventricular tachycardia]], and [[Short QT syndrome]]. Other conditions that promote arrhythmias but are not caused by genetic mutations include [[Wolff–Parkinson–White syndrome|Wolff-Parkinson-White syndrome]].<ref name="UTD2016" />

Long QT syndrome, a condition often mentioned in young people's deaths, occurs in one of every 5000 to 7000 newborns and is estimated to be responsible for 3000 deaths each year compared to the approximately 300,000 cardiac arrests seen by emergency services.<ref name="AHA2">[http://www.americanheart.org/presenter.jhtml?identifier=4741 Sudden Cardiac Death] {{webarchive|url=https://web.archive.org/web/20100325174959/http://www.americanheart.org/presenter.jhtml?identifier=4741|date=2010-03-25}}</ref> These conditions are a fraction of the overall deaths related to cardiac arrest but represent conditions which may be detected prior to arrest and may be treatable.

===Non-cardiac causes===
SCA due to non-cardiac causes accounts for the remaining 15 to 25%.<ref name=":4" /><ref name="ReferenceA">{{cite journal | vauthors = Kuisma M, Alaspää A | title = Out-of-hospital cardiac arrests of non-cardiac origin. Epidemiology and outcome | journal = European Heart Journal | volume = 18 | issue = 7 | pages = 1122–8 | date = July 1997 | pmid = 9243146 | doi = 10.1093/oxfordjournals.eurheartj.a015407 | doi-access = free }}</ref> The most common non-cardiac causes are [[Physical trauma|trauma]], major [[bleeding]] ([[gastrointestinal bleeding]], [[aortic rupture]], or [[intracranial hemorrhage]]), [[hypovolemic shock]], [[overdose]], [[drowning]], and [[pulmonary embolism]].<ref name="ReferenceA" /><ref name=Raab2008>{{cite journal | last1=Raab | first1=Helmut | last2=Lindner | first2=Karl H. | last3=Wenzel | first3=Volker | title=Preventing cardiac arrest during hemorrhagic shock with vasopressin | journal=Critical Care Medicine | publisher=Ovid Technologies (Wolters Kluwer Health) | volume=36 | issue=Suppl | year=2008 | issn=0090-3493 | pmid=20449913 | doi=10.1097/ccm.0b013e31818a8d7e | pages=S474–S480}}</ref><ref name=Voel2000>{{cite journal | last1=Voelckel | first1=Wolfgang G. | last2=Lurie | first2=Keith G. | last3=Lindner | first3=Karl H. | last4=Zielinski | first4=Todd | last5=McKnite | first5=Scott | last6=Krismer | first6=Anette C. | last7=Wenzel | first7=Volker | title=Vasopressin Improves Survival After Cardiac Arrest in Hypovolemic Shock | journal=Anesthesia & Analgesia | volume=91 | issue=3 | publisher=Ovid Technologies (Wolters Kluwer Health) | year=2000 | issn=0003-2999 | doi=10.1097/00000539-200009000-00024 | pmid=10960389 | pages=627–634}}</ref> Cardiac arrest can also be caused by poisoning (for example, by the [[Jellyfish#Toxicity|stings of certain jellyfish]]), or through electrocution, or other medical causes such as [[Thyroid Storm]]<ref name="HaleMildenhall2021">{{cite journal|last1=Hale|first1=Matthew|last2=Mildenhall|first2=Jo|last3=Hook|first3=Christopher|last4=Burt|first4=James|title=Clinical case review: out-of-hospital cardiac arrest following thyroid storm|journal=Journal of Paramedic Practice|volume=13|issue=4|year=2021|pages=144–150|issn=1759-1376|doi=10.12968/jpar.2021.13.4.144}}</ref>
.<ref name=":6" />

===Mnemonic for reversible causes===
{{Main|Hs and Ts}}"Hs and Ts" is the name for a mnemonic used to aid in remembering the possible treatable or reversible causes of cardiac arrest.<ref name="RCUK20052">{{cite web|url=http://www.resus.org.uk/pages/guide.htm|title=Resuscitation Council (UK) Guidelines 2005|archive-url=https://web.archive.org/web/20091215230632/http://www.resus.org.uk/pages/guide.htm|archive-date=2009-12-15|url-status=live}}</ref><ref name="AHA052">{{cite journal | title = 2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 112 | issue = 24 Suppl | pages = IV1-203 | date = December 2005 | pmid = 16314375 | doi = 10.1161/CIRCULATIONAHA.105.166550| last1 = Ecc Committee | first1 = Subcommittees Task Forces of the American Heart Association | doi-access = free }}</ref><ref name=":3" />

; Hs
* [[Hypovolemia|'''H'''ypovolemia]] – A lack of blood volume
* [[Hypoxia (medical)|'''H'''ypoxia]] – A lack of [[oxygen]]
* [[Hydrogen|'''H'''ydrogen]] ions ([[Acidosis]]) – An abnormal pH in the body
* [[Hyperkalemia|'''H'''yperkalemia]] or [[Hypokalemia|'''H'''ypokalemia]] – Both increased or decreased [[potassium]] can be life-threatening.
* [[Hypothermia|'''H'''ypothermia]] – A low [[Body temperature|core body temperature]]
* [[Hypoglycemia|'''H'''ypoglycemia]] or [[Hyperglycemia|'''H'''yperglycemia]] – Low or high blood glucose
; Ts
* [[Tablet (pharmacy)|'''T'''ablets]] or [[Toxins|'''T'''oxins]] such as drug overdose
* [[Cardiac tamponade|Cardiac '''T'''amponade]] – Fluid building up around the heart
* [[Tension pneumothorax|'''T'''ension pneumothorax]] – A collapsed lung
* [[Thrombosis|'''T'''hrombosis]] ([[Myocardial infarction]]) – Heart attack
* [[Thrombosis|'''T'''hromboembolism]] ([[Pulmonary embolism]]) – A blood clot in the lung
* [[Traumatic cardiac arrest|'''T'''raumatic cardiac arrest]]

=== Children ===
In children, the most common cause of cardiopulmonary arrest is [[Shock (circulatory)|shock]] or [[respiratory failure]] that has not been treated, rather than a [[heart arrhythmia]].<ref name=":6" /> When there is a cardiac arrhythmia, it is most often [[asystole]] or [[bradycardia]], in contrast to [[ventricular fibrillation]] or [[Ventricular tachycardia|tachycardia]] as seen in adults.<ref name=":6" /> Other causes can include drugs such as [[Cocaine intoxication|cocaine]], [[methamphetamine]], or overdose of medications such as antidepressants in a child who was previously healthy but is now presenting with a dysrhythmia that has progressed to cardiac arrest.<ref name=":6" />

=== Risk factors ===
The risk factors for SCD are similar to those of coronary artery disease and include age, cigarette smoking, high blood pressure, high cholesterol, lack of [[physical exercise]], [[obesity]], [[diabetes]], and [[family history]].<ref>{{cite journal | vauthors = Friedlander Y, Siscovick DS, Weinmann S, Austin MA, Psaty BM, Lemaitre RN, Arbogast P, Raghunathan TE, Cobb LA | title = Family history as a risk factor for primary cardiac arrest | journal = Circulation | volume = 97 | issue = 2 | pages = 155–60 | date = January 1998 | pmid = 9445167 | doi = 10.1161/01.cir.97.2.155 | doi-access = free }}</ref> A prior episode of sudden cardiac arrest also increases the risk of future episodes.<ref>{{cite book|title=Harrison's principles of internal medicine. | first1 = Dennis L | last1 = Kasper | first2 = Anthony S | last2 = Fauci | first3 = Stephen L | last3 = Hauser | first4 = Dan L | last4 = Longo | first5 = J Larry | last5 = Jameson | first6 = Joseph | last6 = Loscalzo | name-list-style = vanc |year=2014|isbn=9780071802154|edition=19th|location=New York|chapter=327. Cardiovascular Collapse, Cardiac Arrest, and Sudden Cardiac Death|oclc=893557976}}</ref>

[[Air pollution]] is also associated with the risk of cardiac arrest.<ref>{{cite journal | vauthors = Teng TH, Williams TA, Bremner A, Tohira H, Franklin P, Tonkin A, Jacobs I, Finn J | title = A systematic review of air pollution and incidence of out-of-hospital cardiac arrest | journal = Journal of Epidemiology and Community Health | volume = 68 | issue = 1 | pages = 37–43 | date = January 2014 | pmid = 24101168 | doi = 10.1136/jech-2013-203116 | hdl = 20.500.11937/11721 | s2cid = 26111030 | hdl-access = free }}</ref> Current cigarette smokers with coronary artery disease were found to have a two to threefold increase in the risk of sudden death between ages 30 and 59. Furthermore, it was found that former smokers’ risk was closer to that of those who had never smoked.<ref name=":2" /><ref>{{cite journal | vauthors = Goldenberg I, Jonas M, Tenenbaum A, Boyko V, Matetzky S, Shotan A, Behar S, Reicher-Reiss H | title = Current smoking, smoking cessation, and the risk of sudden cardiac death in patients with coronary artery disease | journal = Archives of Internal Medicine | volume = 163 | issue = 19 | pages = 2301–5 | date = October 2003 | pmid = 14581249 | doi = 10.1001/archinte.163.19.2301 | doi-access = free }}</ref>

==Mechanism==
[[File:Ventricular fibrillation.png|thumb|upright=1.3|Ventricular fibrillation]]
The mechanism responsible for the majority of sudden cardiac deaths is [[ventricular fibrillation]].<ref name=NIH2016Ca/> Structural changes in the diseased heart as a result of inherited factors (mutations in ion-channel coding genes for example) cannot explain the suddenness of SCD.<ref>{{cite journal | vauthors = Rubart M, Zipes DP | title = Mechanisms of sudden cardiac death | journal = The Journal of Clinical Investigation | volume = 115 | issue = 9 | pages = 2305–15 | date = September 2005 | pmid = 16138184 | pmc = 1193893 | doi = 10.1172/JCI26381 }}</ref> Also, sudden cardiac death could be the consequence of [[Electrical conduction system of the heart|electric-mechanical disjunction]] and [[bradyarrhythmia]]s.<ref>{{cite journal | vauthors = Bunch TJ, Hohnloser SH, Gersh BJ | title = Mechanisms of sudden cardiac death in myocardial infarction survivors: insights from the randomized trials of implantable cardioverter-defibrillators | journal = Circulation | volume = 115 | issue = 18 | pages = 2451–7 | date = May 2007 | pmid = 17485594 | doi = 10.1161/CIRCULATIONAHA.106.683235 | doi-access = free }}</ref><ref>{{cite web |title = Types of Arrhythmia |publisher = National Heart, Lung and Blood Institute |url = http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types |date = 1 April 2011 |access-date = 2015-06-21 |url-status = dead |archive-url = https://web.archive.org/web/20150607165144/http://www.nhlbi.nih.gov/health/health-topics/topics/arr/types |archive-date = 7 June 2015 }}</ref>

==Diagnosis==
Cardiac arrest is synonymous with [[clinical death]].<ref name="AHA05" /> Historical information and a physical exam diagnosis cardiac arrest, as well as provides information regarding the potential cause and the prognosis.<ref name=":6" /> The history should aim to determine if the episode was observed by anyone else, what time the episode took place, what the person was doing (in particular if there was any trauma), and involvement of drugs.<ref name=":6" />

The physical examination portion of diagnosis cardiac arrest focuses on the absence of a pulse clinically.<ref name=":6" /> In many cases lack of [[pulse|carotid pulse]] is the [[gold standard (test)|gold standard]] for diagnosing cardiac arrest, as lack of a pulse (particularly in the peripheral pulses) may result from other conditions (e.g. [[Shock (circulatory)|shock]]), or simply an error on the part of the rescuer.<ref name=":7" /> Nonetheless, studies have shown that rescuers often make a mistake when checking the carotid pulse in an emergency, whether they are healthcare professionals<ref name=":7">{{cite journal | vauthors = Ochoa FJ, Ramalle-Gómara E, Carpintero JM, García A, Saralegui I | title = Competence of health professionals to check the carotid pulse | journal = Resuscitation | volume = 37 | issue = 3 | pages = 173–5 | date = June 1998 | pmid = 9715777 | doi = 10.1016/S0300-9572(98)00055-0 }}</ref> or lay persons.<ref>{{cite journal | vauthors = Bahr J, Klingler H, Panzer W, Rode H, Kettler D | title = Skills of lay people in checking the carotid pulse | journal = Resuscitation | volume = 35 | issue = 1 | pages = 23–6 | date = August 1997 | pmid = 9259056 | doi = 10.1016/S0300-9572(96)01092-1 }}</ref>

Owing to the inaccuracy in this method of diagnosis, some bodies such as the European Resuscitation Council (ERC) have de-emphasised its importance. The Resuscitation Council (UK), in line with the ERC's recommendations and those of the American Heart Association,<ref name="AHA05">{{cite journal | title = 2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 112 | issue = 24 Suppl | pages = IV1-203 | date = December 2005 | pmid = 16314375 | doi = 10.1161/CIRCULATIONAHA.105.166550| last1 = Ecc Committee | first1 = Subcommittees Task Forces of the American Heart Association | doi-access = free }}</ref> have suggested that the technique should be used only by healthcare professionals with specific training and expertise, and even then that it should be viewed in conjunction with other indicators such as [[agonal respiration]].<ref name="RCUK2005">{{cite web |url=http://www.resus.org.uk/pages/guide.htm |title=Resuscitation Council (UK) Guidelines 2005 |url-status=live |archive-url=https://web.archive.org/web/20091215230632/http://www.resus.org.uk/pages/guide.htm |archive-date=2009-12-15 }}</ref>

Various other methods for detecting circulation have been proposed. Guidelines following the 2000 International Liaison Committee on Resuscitation (ILCOR) recommendations were for rescuers to look for "signs of circulation", but not specifically the pulse.<ref name=AHA05/> These signs included coughing, gasping, colour, twitching, and movement.<ref>{{cite book |author=British Red Cross; St Andrew's Ambulance Association; St John Ambulance |title=First Aid Manual: The Authorised Manual of St. John Ambulance, St. Andrew's Ambulance Association, and the British Red Cross |publisher=Dorling Kindersley Publishers Ltd |year=2006 |isbn=978-1-4053-1573-9 |url-access=registration |url=https://archive.org/details/firstaidmanualau0000unse }}</ref> However, in face of evidence that these guidelines were ineffective, the current recommendation of ILCOR is that cardiac arrest should be diagnosed in all casualties who are unconscious and not breathing normally.<ref name=AHA05/> Another method is to use [[molecular autopsy]] or postmortem molecular testing which uses a set of molecular techniques to find the ion channels that are cardiac defective.<ref>{{Citation|last1=Glatter|first1=Kathryn A.|title=Postmortem Analysis for Inherited Ion Channelopathies|date=2006|work=Essentials of Autopsy Practice: Current Methods and Modern Trends|pages=15–37|editor-last=Rutty|editor-first=Guy N.|publisher=Springer|language=en|doi=10.1007/1-84628-026-5_2|isbn=978-1-84628-026-9|last2=Chiamvimonvat|first2=Nipavan|last3=He|first3=Yuxia|last4=Chevalier|first4=Philippe|last5=Turillazzi|first5=Emanuela}}</ref>

Other physical findings can help determine the potential cause of the cardiac arrest.<ref name=":6" />

<br />
{|
|+Physical findings related to potential causes<ref name=":6" />
!Location
!Findings
!Possible Causes
|-
|General
|Pale skin
|[[Bleeding|Hemorrhage]]
|-
|
|Decreased body temperature
|[[Hypothermia]]
|-
|Airway
|Presence of secretions, vomit, blood
|[[Pulmonary aspiration|Aspiration]]
|-
|
|Inability to provide [[Modes of mechanical ventilation|positive pressure ventilation]]
|[[Pneumothorax|Tension pneumothorax]]
[[Airway obstruction]]
|-
|Neck
|[[Jugular venous pressure|Distension of the neck veins]]
|Tension pneumothorax
[[Cardiac tamponade]]

[[Pulmonary embolism]]
|-
|
|[[Tracheal deviation|Trachea shifted to one side]] 
|Tension pneumothorax
|-
|Chest
|[[Median sternotomy|Scar in the middle of the sternum]]
|Cardiac disease
|-
|Lungs
|[[Respiratory sounds|Breath sounds only on one side]]
|Tension pneumothorax
[[Tracheal intubation|Right mainstem intubation]]

Aspiration
|-
|
|No breath sounds or distant breath sounds
|Esophageal intubation

Airway obstruction
|-
|
|[[Wheeze|Wheezing]] 
|Aspiration

[[Bronchospasm]]

[[Pulmonary edema]]
|-
|
|[[Crackles|Rales]]
|Aspiration

Pulmonary edema

Pneumonia
|-
|Heart
|Decreased heart sounds
|[[Hypovolemia]]

Cardiac tamponade

Tension pneumothorax

Pulmonary embolus
|-
|Abdomen
|[[Distended]] and dull 
|Ruptured [[abdominal aortic aneurysm]]

Ruptured [[ectopic pregnancy]]
|-
|
|Distended and [[wikt:tympanic|tympanic]]
|Esophageal intubation
|-
|Rectal
|Blood present
|[[Gastrointestinal bleeding|Gastrointestinal hemorrhage]] 
|-
|Extremities
|Asymmetrical pulses
|[[Aortic dissection]]
|-
|Skin
|Needle tracks
|Drug abuse
|}

===Classifications===
Clinicians classify cardiac arrest into "shockable" versus "non-shockable", as determined by the [[Electrocardiogram|ECG]] rhythm. This refers to whether a particular class of [[cardiac dysrhythmia]] is treatable using [[defibrillation]].<ref name="RCUK2005"/> The two "shockable" rhythms are [[ventricular fibrillation]] and [[pulseless ventricular tachycardia]] while the two "non-shockable" rhythms are [[asystole]] and [[pulseless electrical activity]].<ref>{{cite book|title=ABC of resuscitation| veditors = Soar J, Perkins JD, Nolan J |year=2012|publisher=Wiley-Blackwell|location=Chichester, West Sussex |isbn=9781118474853 |page=43 |url= https://books.google.com/books?id=vNgrOsHjIKEC&pg=PA43 |edition=6th |url-status=live |archive-url=https://web.archive.org/web/20170905133735/https://books.google.com/books?id=vNgrOsHjIKEC&pg=PA43|archive-date=2017-09-05}}</ref>

==Prevention==
With positive outcomes following cardiac arrest unlikely, an effort has been spent in finding effective strategies to prevent cardiac arrest. With the prime causes of cardiac arrest being [[ischemic heart disease]], efforts to promote a [[healthy diet]], [[exercise]], and [[smoking cessation]] are important. For people at risk of heart disease, measures such as [[blood pressure]] control, [[cholesterol]] lowering, and other medico-therapeutic interventions are used.{{ref}} A [[Cochrane review]] published in 2016 found moderate-quality evidence to show that blood pressure-lowering drugs do not appear to reduce sudden cardiac death.<ref>{{cite journal | vauthors = Taverny G, Mimouni Y, LeDigarcher A, Chevalier P, Thijs L, Wright JM, Gueyffier F | title = Antihypertensive pharmacotherapy for prevention of sudden cardiac death in hypertensive individuals | journal = The Cochrane Database of Systematic Reviews | volume = 3 | pages = CD011745 | date = March 2016 | pmid = 26961575 | doi = 10.1002/14651858.CD011745.pub2 }}</ref>

===Code teams===
In medical parlance, cardiac arrest is referred to as a "code" or a "crash". This typically refers to "code blue" on the [[hospital emergency codes]]. A dramatic drop in vital sign measurements is referred to as "coding" or "crashing", though coding is usually used when it results in cardiac arrest, while crashing might not. Treatment for cardiac arrest is sometimes referred to as "calling a code".

People in general wards often deteriorate for several hours or even days before a cardiac arrest occurs.<ref name="RCUK2005" /><ref name="Kause et al. 2004">{{cite journal | vauthors = Kause J, Smith G, Prytherch D, Parr M, Flabouris A, Hillman K | title = A comparison of antecedents to cardiac arrests, deaths and emergency intensive care admissions in Australia and New Zealand, and the United Kingdom—the ACADEMIA study | journal = Resuscitation | volume = 62 | issue = 3 | pages = 275–82 | date = September 2004 | pmid = 15325446 | doi = 10.1016/j.resuscitation.2004.05.016 }}</ref> This has been attributed to a lack of knowledge and skill amongst ward-based staff, in particular, a failure to carry out measurement of the [[respiratory rate]], which is often the major predictor of a deterioration<ref name="RCUK2005" /> and can often change up to 48 hours prior to a cardiac arrest. In response to this, many hospitals now have increased training for ward-based staff. A number of "early warning" systems also exist which aim to quantify the person's risk of deterioration based on their [[vital signs]] and thus provide a guide to staff. In addition, specialist staff are being used more effectively in order to augment the work already being done at ward level. These include:
* Crash teams (or code teams) – These are designated staff members with particular expertise in resuscitation who are called to the scene of all arrests within the hospital. This usually involves a specialized cart of equipment (including [[defibrillation|defibrillator]]) and drugs called a "[[crash cart]]" or "crash trolley".
* [[Medical emergency team]]s – These teams respond to all emergencies, with the aim of treating the people in the acute phase of their illness in order to prevent a cardiac arrest. These teams have been found to decrease the rates of in-hospital cardiac arrest and improve survival.<ref name=AHA2015Part4/>
* Critical care outreach – As well as providing the services of the other two types of team, these teams are also responsible for educating non-specialist staff. In addition, they help to facilitate transfers between [[Intensive care unit|intensive care/high dependency units]] and the general hospital wards. This is particularly important, as many studies have shown that a significant percentage of patients discharged from critical care environments quickly deteriorate and are re-admitted; the outreach team offers support to ward staff to prevent this from happening.{{citation needed|date=December 2017}}

===Implantable cardioverter defibrillator===
[[File:Blausen_0543_ImplantableCardioverterDefibrillator_InsideLeads.png|upright=1.3|thumb|Illustration of implantable cardioverter defibrillator (ICD)]]
An [[Implantable cardioverter-defibrillator|implantable cardioverter defibrillator]] (ICD) is a battery-powered device that monitors electrical activity in the heart and when an arrhythmia or asystole is detected is able to deliver an electrical shock to terminate the abnormal rhythm. ICDs are used to prevent sudden cardiac death (SCD) in those that have survived a prior episode of sudden cardiac arrest (SCA) due to ventricular fibrillation or ventricular tachycardia ([[secondary prevention]]).<ref name=":10">{{cite journal | vauthors = Epstein AE, DiMarco JP, Ellenbogen KA, Estes NA, Freedman RA, Gettes LS, Gillinov AM, Gregoratos G, Hammill SC, Hayes DL, Hlatky MA, Newby LK, Page RL, Schoenfeld MH, Silka MJ, Stevenson LW, Sweeney MO, Smith SC, Jacobs AK, Adams CD, Anderson JL, Buller CE, Creager MA, Ettinger SM, Faxon DP, Halperin JL, Hiratzka LF, Hunt SA, Krumholz HM, Kushner FG, Lytle BW, Nishimura RA, Ornato JP, Page RL, Riegel B, Tarkington LG, Yancy CW | title = ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices): developed in collaboration with the American Association for Thoracic Surgery and Society of Thoracic Surgeons | journal = Circulation | volume = 117 | issue = 21 | pages = e350-408 | date = May 2008 | pmid = 18483207 | doi = 10.1161/CIRCUALTIONAHA.108.189742 | doi-access = free }}</ref> ICD's are also used prophylactically to prevent sudden cardiac death in certain high risk patient populations ([[Preventive healthcare|primary prevention]]).<ref name=":11">{{cite journal | vauthors = Shun-Shin MJ, Zheng SL, Cole GD, Howard JP, Whinnett ZI, Francis DP | title = Implantable cardioverter defibrillators for primary prevention of death in left ventricular dysfunction with and without ischaemic heart disease: a meta-analysis of 8567 patients in the 11 trials | journal = European Heart Journal | volume = 38 | issue = 22 | pages = 1738–1746 | date = June 2017 | pmid = 28329280 | pmc = 5461475 | doi = 10.1093/eurheartj/ehx028 }}</ref>

Numerous studies have been conducted on the use of ICDs for the secondary prevention of SCD. These studies have shown improved survival with ICD's compared to the use of anti-arrhythmic drugs.<ref name=":10" /> ICD therapy is associated with a 50% [[relative risk reduction]] in death caused by an arrhythmia and a 25% relative risk reduction in all cause mortality.<ref>{{cite journal | vauthors = Connolly SJ, Hallstrom AP, Cappato R, Schron EB, Kuck KH, Zipes DP, Greene HL, Boczor S, Domanski M, Follmann D, Gent M, Roberts RS | title = Meta-analysis of the implantable cardioverter defibrillator secondary prevention trials. AVID, CASH and CIDS studies. Antiarrhythmics vs Implantable Defibrillator study. Cardiac Arrest Study Hamburg . Canadian Implantable Defibrillator Study | journal = European Heart Journal | volume = 21 | issue = 24 | pages = 2071–8 | date = December 2000 | pmid = 11102258 | doi = 10.1053/euhj.2000.2476 | doi-access = free }}</ref>

Primary prevention of SCD with ICD therapy for high-risk patient populations has similarly shown improved survival rates in a number of large studies. The high-risk patient populations in these studies were defined as those with severe [[ischemic cardiomyopathy]] (determined by a reduced [[Ejection fraction|left ventricular ejection fraction]] (LVEF)). The LVEF criteria used in these trials ranged from less than or equal to 30% in MADIT-II to less than or equal to 40% in MUSTT.<ref name=":10" /><ref name=":11" />

===Diet===
Marine-derived [[Omega 3 fatty acid|omega-3 polyunsaturated fatty acids]] (PUFAs) have been promoted for the prevention of sudden cardiac death due to their postulated ability to lower [[triglyceride]] levels, prevent [[Heart arrhythmia|arrhythmia]]s, decrease [[platelet aggregation]], and lower blood pressure.<ref>{{cite encyclopedia |title=Omega-3 fatty acids |encyclopedia=MedlinePlus Medical Encyclopedia | first = Neil K. | last = Kaneshiro | name-list-style = vanc |url=https://www.nlm.nih.gov/medlineplus/ency/imagepages/19302.htm |date=2 August 2011 |access-date=2015-06-21 |url-status=live |archive-url=https://web.archive.org/web/20150621170015/http://www.nlm.nih.gov/medlineplus/ency/imagepages/19302.htm |archive-date=21 June 2015 }}</ref> However, according to a recent systematic review, omega-3 PUFA supplementation are not being associated with a lower risk of sudden cardiac death.<ref name=JAMA2012>{{cite journal | vauthors = Rizos EC, Ntzani EE, Bika E, Kostapanos MS, Elisaf MS | title = Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events: a systematic review and meta-analysis | journal = JAMA | volume = 308 | issue = 10 | pages = 1024–33 | date = September 2012 | pmid = 22968891 | doi = 10.1001/2012.jama.11374 }}</ref>

==Management==
Sudden cardiac arrest may be treated via attempts at [[resuscitation]]. This is usually carried out based upon [[basic life support]], [[advanced cardiac life support]] (ACLS), [[pediatric advanced life support]] (PALS), or [[neonatal resuscitation program]] (NRP) guidelines.<ref name="AHA05"/><ref>{{cite journal | title = 2005 American Heart Association (AHA) guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) of pediatric and neonatal patients: pediatric advanced life support | journal = Pediatrics | volume = 117 | issue = 5 | pages = e1005-28 | date = May 2006 | pmid = 16651281 | doi = 10.1542/peds.2006-0346 | author1 = American Heart Association | s2cid = 46720891 }}</ref>

===Cardiopulmonary resuscitation===
Early [[cardiopulmonary resuscitation]] (CPR) is essential to surviving cardiac arrest with good neurological function.<ref>{{cite web |title=AHA Releases 2015 Heart and Stroke Statistics {{!}} Sudden Cardiac Arrest Foundation |url=https://www.sca-aware.org/sca-news/aha-releases-2015-heart-and-stroke-statistics |website=www.sca-aware.org |access-date=21 September 2019}}</ref><ref name=":6">{{Cite book|title=Rosen's emergency medicine : concepts and clinical practice|last=Walls, Ron M., editor. Hockberger, Robert S., editor. Gausche-Hill, Marianne, editor.|isbn=9780323390163|oclc=989157341|date = 2017-03-09}}</ref> It is recommended that it be started as soon as possible with minimal interruptions once begun. The components of CPR that make the greatest difference in survival are [[chest compressions]] and defibrillating shockable rhythms.<ref name=":3">{{Cite book|title=Tintinalli's emergency medicine manual|last=Cydulka, Rita K., editor.|isbn=9780071837026|oclc=957505642|date = 2017-08-28}}</ref> After defibrillation, chest compressions should be continued for two minutes before a rhythm check is again done.<ref name=":6" /> This is based on a compression rate of 100-120 compressions per minute, a compression depth of 5–6 centimeters into the chest, full [[Cardiopulmonary resuscitation|chest recoil]], and a ventilation rate of 10 breath ventilations per minute.<ref name=":6" /> Correctly performed bystander CPR has been shown to increase survival; however, it is performed in less than 30% of out of hospital arrests {{as of|2007|lc=y}}.<ref name="Mutchner L 2007 60–9; quiz 69–70"/> If high-quality CPR has not resulted in [[return of spontaneous circulation]] and the person's heart rhythm is in [[asystole]], discontinuing CPR and pronouncing the person's death is reasonable after 20 minutes.<ref name=UK2010/> Exceptions to this include certain cases with [[hypothermia]] or who have [[drowning|drowned]].<ref name=":3" /><ref name=UK2010>{{cite web|author1=Resuscitation Council (UK)|title=Pre-hospital cardiac arrest|url=https://www.resus.org.uk/pages/prehosca.pdf|website=www.resus.org.uk|access-date=3 September 2014|page=41|url-status=live|archive-url=https://web.archive.org/web/20150513032323/http://www.resus.org.uk/pages/prehosca.pdf|archive-date=13 May 2015}}</ref> Some of these cases should have longer and more sustained CPR until they are nearly [[Normothermia|normothermic]].<ref name=":3" /> Longer durations of CPR may be reasonable in those who have cardiac arrest while in hospital.<ref>{{cite web|author1=Resuscitation Council (UK)|title=Comments on the duration of CPR following the publication of 'Duration of resuscitation efforts and survival after in-hospital cardiac arrest: an observational study' Goldberger ZD et al. Lancet.|url=https://www.resus.org.uk/pages/cprdurst.htm|access-date=3 September 2014|date=5 September 2012|url-status=dead|archive-url=https://web.archive.org/web/20140628095645/http://resus.org.uk/pages/cprdurst.htm|archive-date=28 June 2014}}</ref> [[Bystander CPR]], by the lay public, before the arrival of EMS also improves outcomes.<ref name=AHA2015Part4/>

<!-- Airway -->
Either a [[bag valve mask]] or an [[advanced airway]] may be used to help with breathing particularly since vomiting and regurgitation are common, particularly in out-of-hospital cardiac arrest (OHCA).<ref name=AHA2015Part1/><ref>{{Cite journal| doi = 10.1016/j.resuscitation.2007.01.038| issn = 0300-9572| volume = 74| issue = 3| pages = 427–431| last1 = Simons| first1 = Reed W.| last2 = Rea| first2 = Thomas D.| last3 = Becker| first3 = Linda J.| last4 = Eisenberg| first4 = Mickey S.| title = The incidence and significance of emesis associated with out-of-hospital cardiac arrest| journal = Resuscitation| date = September 2007| pmid = 17433526}}</ref><ref>
{{Cite journal| doi = 10.1016/j.resuscitation.2014.09.008| issn = 0300-9572, 1873-1570| volume = 85| issue = 12| pages = 1662–1666| last1 = Voss| first1 = Sarah| last2 = Rhys| first2 = Megan| last3 = Coates| first3 = David| last4 = Greenwood| first4 = Rosemary| last5 = Nolan| first5 = Jerry P.| last6 = Thomas| first6 = Matthew| last7 = Benger| first7 = Jonathan| title = How do paramedics manage the airway during out of hospital cardiac arrest?| journal = Resuscitation| access-date = 2019-03-04| date = 2014-12-01| url = https://www.resuscitationjournal.com/article/S0300-9572(14)00749-7/abstract| pmid = 25260723| pmc = 4265730}}</ref> If this occurs, then modification to existing oropharyngeal suction may be required, such as the use of [[Suction Assisted Laryngoscopy Airway Decontamination]].<ref>
{{Cite journal| doi = 10.1016/j.resplu.2020.100005| issn = 2666-5204| volume = 1-2| pages = 100005| last1 = Root| first1 = Christopher W.| last2 = Mitchell| first2 = Oscar J. L.| last3 = Brown| first3 = Russ| last4 = Evers| first4 = Christopher B.| last5 = Boyle| first5 = Jess| last6 = Griffin| first6 = Cynthia| last7 = West| first7 = Frances Mae| last8 = Gomm| first8 = Edward| last9 = Miles| first9 = Edward| last10 = McGuire| first10 = Barry| last11 = Swaminathan| first11 = Anand| last12 = St George| first12 = Jonathan| last13 = Horowitz| first13 = James M.| last14 = DuCanto| first14 = James| title = Suction Assisted Laryngoscopy and Airway Decontamination (SALAD): A technique for improved emergency airway management| journal = Resuscitation Plus| access-date = 2020-10-25| date = 2020-03-01| url = http://www.sciencedirect.com/science/article/pii/S2666520420300059| doi-access = free}}</ref> High levels of oxygen are generally given during CPR.<ref name=AHA2015Part1>{{cite journal | vauthors = Neumar RW, Shuster M, Callaway CW, Gent LM, Atkins DL, Bhanji F, Brooks SC, de Caen AR, Donnino MW, Ferrer JM, Kleinman ME, Kronick SL, Lavonas EJ, Link MS, Mancini ME, Morrison LJ, O'Connor RE, Samson RA, Schexnayder SM, Singletary EM, Sinz EH, Travers AH, Wyckoff MH, Hazinski MF | title = Part 1: Executive Summary: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 132 | issue = 18 Suppl 2 | pages = S315-67 | date = November 2015 | pmid = 26472989 | doi = 10.1161/cir.0000000000000252 | doi-access = free }}</ref> [[Tracheal intubation]] has not been found to improve survival rates or neurological outcome in cardiac arrest<ref name="Mutchner L 2007 60–9; quiz 69–70">{{cite journal | vauthors = Mutchner L | title = The ABCs of CPR—again | journal = The American Journal of Nursing | volume = 107 | issue = 1 | pages = 60–9; quiz 69–70 | date = January 2007 | pmid = 17200636 | doi = 10.1097/00000446-200701000-00024 }}</ref><ref name="White L 2018">{{cite journal | vauthors = White L, Melhuish T, Holyoak R, Ryan T, Kempton H, Vlok R | s2cid = 52931036 | title = Advanced airway management in out of hospital cardiac arrest: A systematic review and meta-analysis | journal = The American Journal of Emergency Medicine | volume = 36 | issue = 12 | pages = 2298–2306 | date = December 2018 | pmid = 30293843 | doi = 10.1016/j.ajem.2018.09.045 | url = https://espace.library.uq.edu.au/view/UQ:4f65350/UQ4f65350_OA.pdf }}</ref> and in the prehospital environment may worsen it.<ref>{{cite journal | vauthors = Studnek JR, Thestrup L, Vandeventer S, Ward SR, Staley K, Garvey L, Blackwell T | title = The association between prehospital endotracheal intubation attempts and survival to hospital discharge among out-of-hospital cardiac arrest patients | journal = Academic Emergency Medicine | volume = 17 | issue = 9 | pages = 918–25 | date = September 2010 | pmid = 20836771 | doi = 10.1111/j.1553-2712.2010.00827.x | doi-access = free }}</ref> Endotracheal tube and [[supraglottic airway]]s appear equally useful.<ref name="White L 2018"/> When done by EMS 30 compressions followed by two breaths appear better than continuous chest compressions and breaths being given while compressions are ongoing.<ref name=L2017/>

<!-- Compressions -->
For bystanders, CPR which involves only chest compressions results in better outcomes as compared to standard CPR for those who have gone into cardiac arrest due to heart issues.<ref name=L2017>{{cite journal | vauthors = Zhan L, Yang LJ, Huang Y, He Q, Liu GJ | title = Continuous chest compression versus interrupted chest compression for cardiopulmonary resuscitation of non-asphyxial out-of-hospital cardiac arrest | journal = The Cochrane Database of Systematic Reviews | volume = 3 | pages = CD010134 | date = March 2017 | pmid = 28349529 | pmc = 6464160 | doi = 10.1002/14651858.CD010134.pub2 }}</ref> Mechanical chest compressions (as performed by a machine) are no better than chest compressions performed by hand.<ref name=AHA2015Part1/> It is unclear if a few minutes of CPR before defibrillation results in different outcomes than immediate defibrillation.<ref>{{cite journal | vauthors = Huang Y, He Q, Yang LJ, Liu GJ, Jones A | title = Cardiopulmonary resuscitation (CPR) plus delayed defibrillation versus immediate defibrillation for out-of-hospital cardiac arrest | journal = The Cochrane Database of Systematic Reviews | volume = 9 | issue = 9 | pages = CD009803 | date = September 2014 | pmid = 25212112 | doi = 10.1002/14651858.CD009803.pub2 | pmc = 6516832 }}</ref> If cardiac arrest occurs after 20 weeks of pregnancy someone should pull or push the uterus to the left during CPR.<ref name=Lav2015/> If a pulse has not returned by four minutes emergency [[Cesarean section]] is recommended.<ref name=Lav2015/>

===Defibrillation===
[[File:Defibrillator-809447 1920.jpg|thumb|upright=1.3|An automated external defibrillator stored in a visible orange mural support]]
Defibrillation is indicated if a shockable rhythm is present. The two shockable rhythms are [[ventricular fibrillation]] and [[pulseless ventricular tachycardia]]. In children 2 to 4 J/Kg is recommended.<ref name="AHA2015Part12">{{cite journal | vauthors = de Caen AR, Berg MD, Chameides L, Gooden CK, Hickey RW, Scott HF, Sutton RM, Tijssen JA, Topjian A, van der Jagt ÉW, Schexnayder SM, Samson RA | title = Part 12: Pediatric Advanced Life Support: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 132 | issue = 18 Suppl 2 | pages = S526-42 | date = November 2015 | pmid = 26473000 | pmc = 6191296 | doi = 10.1161/cir.0000000000000266 }}</ref>

In addition, there is increasing use of public access defibrillation. This involves placing an [[automated external defibrillator]] in public places, and training staff in these areas how to use them. This allows defibrillation to take place prior to the arrival of emergency services and has been shown to lead to increased chances of survival. Some defibrillators even provide feedback on the quality of CPR compressions, encouraging the lay rescuer to press the person's chest hard enough to circulate blood.<ref>[http://www.lifeassisttraining.com/zollaedplus.html Zoll AED Plus] {{webarchive|url=https://web.archive.org/web/20110621004342/http://www.lifeassisttraining.com/zollaedplus.html|date=2011-06-21}}</ref> In addition, it has been shown that those who have arrests in remote locations have worse outcomes following cardiac arrest.<ref name="Lyon ''et al.'' 2004">{{cite journal | vauthors = Lyon RM, Cobbe SM, Bradley JM, Grubb NR | title = Surviving out of hospital cardiac arrest at home: a postcode lottery? | journal = Emergency Medicine Journal | volume = 21 | issue = 5 | pages = 619–24 | date = September 2004 | pmid = 15333549 | pmc = 1726412 | doi = 10.1136/emj.2003.010363 }}</ref>

===Medications===
[[File:LipidEmulsion.JPG|thumb|upright=1.3|left|Lipid emulsion as used in cardiac arrest due to [[local anesthetic]] agents]]
{{as of|2016}}, medications other than [[epinephrine (medication)|epinephrine]] (adrenaline), while included in guidelines, have not been shown to improve survival to hospital discharge following out-of-hospital cardiac arrest.<ref name=":3" /> This includes the use of [[atropine]], [[lidocaine]], and [[amiodarone]].<ref>{{cite journal | vauthors = Olasveengen TM, Sunde K, Brunborg C, Thowsen J, Steen PA, Wik L | title = Intravenous drug administration during out-of-hospital cardiac arrest: a randomized trial | journal = JAMA | volume = 302 | issue = 20 | pages = 2222–9 | date = November 2009 | pmid = 19934423 | doi = 10.1001/jama.2009.1729 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Lin S, Callaway CW, Shah PS, Wagner JD, Beyene J, Ziegler CP, Morrison LJ | title = Adrenaline for out-of-hospital cardiac arrest resuscitation: a systematic review and meta-analysis of randomized controlled trials | journal = Resuscitation | volume = 85 | issue = 6 | pages = 732–40 | date = June 2014 | pmid = 24642404 | doi = 10.1016/j.resuscitation.2014.03.008 }}</ref><ref>{{cite journal | vauthors = Laina A, Karlis G, Liakos A, Georgiopoulos G, Oikonomou D, Kouskouni E, Chalkias A, Xanthos T | title = Amiodarone and cardiac arrest: Systematic review and meta-analysis | journal = International Journal of Cardiology | volume = 221 | pages = 780–8 | date = October 2016 | pmid = 27434349 | doi = 10.1016/j.ijcard.2016.07.138 }}</ref><ref>{{cite journal | vauthors = McLeod SL, Brignardello-Petersen R, Worster A, You J, Iansavichene A, Guyatt G, Cheskes S | title = Comparative effectiveness of antiarrhythmics for out-of-hospital cardiac arrest: A systematic review and network meta-analysis | journal = Resuscitation | volume = 121 | pages = 90–97 | date = December 2017 | pmid = 29037886 | doi = 10.1016/j.resuscitation.2017.10.012 }}</ref><ref>{{cite journal | vauthors = Ali MU, Fitzpatrick-Lewis D, Kenny M, Raina P, Atkins DL, Soar J, Nolan J, Ristagno G, Sherifali D | title = Effectiveness of antiarrhythmic drugs for shockable cardiac arrest: A systematic review | journal = Resuscitation | volume = 132 | pages = 63–72 | date = November 2018 | pmid = 30179691 | doi = 10.1016/j.resuscitation.2018.08.025 | url = http://wrap.warwick.ac.uk/113491/1/WRAP-effectiveness-antiarrhythmic-drugs-cardiac-review-Nolan-2018.pdf }}</ref><ref name=":3" /> Epinephrine in adults, as of 2019, appears to improve survival but does not appear to improve neurologically normal survival.<ref>{{cite journal |last1=Holmberg |first1=Mathias J. |last2=Issa |first2=Mahmoud S. |last3=Moskowitz |first3=Ari |last4=Morley |first4=Peter |last5=Welsford |first5=Michelle |last6=Neumar |first6=Robert W. |last7=Paiva |first7=Edison F. |last8=Coker |first8=Amin |last9=Hansen |first9=Christopher K. |last10=Andersen |first10=Lars W. |last11=Donnino |first11=Michael W. |last12=Berg |first12=Katherine M. |last13=Böttiger |first13=Bernd W. |last14=Callaway |first14=Clifton W. |last15=Deakin |first15=Charles D. |last16=Drennan |first16=Ian R. |last17=Nicholson |first17=Tonia C. |last18=Nolan |first18=Jerry P. |last19=O’Neil |first19=Brian J. |last20=Parr |first20=Michael J. |last21=Reynolds |first21=Joshua C. |last22=Sandroni |first22=Claudio |last23=Soar |first23=Jasmeet |last24=Wang |first24=Tzong-Luen |title=Vasopressors during adult cardiac arrest: A systematic review and meta-analysis |journal=Resuscitation |date=June 2019 |volume=139 |pages=106–121 |doi=10.1016/j.resuscitation.2019.04.008 |pmid=30980877|doi-access=free }}</ref><ref>{{cite journal |last1=Vargas |first1=M |last2=Buonanno |first2=P |last3=Iacovazzo |first3=C |last4=Servillo |first4=G |title=Epinephrine for out of hospital cardiac arrest: A systematic review and meta-analysis of randomized controlled trials. |journal=Resuscitation |volume=145 |pages=151–157 |date=4 November 2019 |doi=10.1016/j.resuscitation.2019.10.026 |pmid=31693924}}</ref><ref>{{cite journal |last1=Aves |first1=T |last2=Chopra |first2=A |last3=Patel |first3=M |last4=Lin |first4=S |title=Epinephrine for Out-of-Hospital Cardiac Arrest: An Updated Systematic Review and Meta-Analysis. |journal=Critical Care Medicine |date=27 November 2019 |doi=10.1097/CCM.0000000000004130 |pmid=31789700 |volume=48 |pages=225–229|s2cid=208537959 }}</ref> It is generally recommended every five minutes.<ref name=AHA2015Part1/> [[Vasopressin]] overall does not improve or worsen outcomes compared to epinephrine.<ref name=AHA2015Part1/> The combination of epinephrine, vasopressin, and [[methylprednisolone]] appears to improve outcomes.<ref>{{cite journal | vauthors = Belletti A, Benedetto U, Putzu A, Martino EA, Biondi-Zoccai G, Angelini GD, Zangrillo A, Landoni G | title = Vasopressors During Cardiopulmonary Resuscitation. A Network Meta-Analysis of Randomized Trials | journal = Critical Care Medicine | volume = 46 | issue = 5 | pages = e443–e451 | date = May 2018 | pmid = 29652719 | doi = 10.1097/CCM.0000000000003049 | s2cid = 4851288 | url = https://www.zora.uzh.ch/id/eprint/162689/1/document%282%29.pdf }}</ref> Some of the lack of long-term benefit may be related to delays in epinephrine use.<ref>{{cite journal | vauthors = Attaran RR, Ewy GA | title = Epinephrine in resuscitation: curse or cure? | journal = Future Cardiology | volume = 6 | issue = 4 | pages = 473–82 | date = July 2010 | pmid = 20608820 | doi = 10.2217/fca.10.24 }}</ref> While evidence does not support its use in children, guidelines state its use is reasonable.<ref name=AHA2015Part12/><ref name=":3" /> Lidocaine and amiodarone are also deemed reasonable in children with cardiac arrest who have a shockable rhythm.<ref name=AHA2015Part1/><ref name=AHA2015Part12/> The general use of [[sodium bicarbonate]] or [[calcium]] is not recommended.<ref name=AHA2015Part1/><ref>{{cite journal | vauthors = Velissaris D, Karamouzos V, Pierrakos C, Koniari I, Apostolopoulou C, Karanikolas M | title = Use of Sodium Bicarbonate in Cardiac Arrest: Current Guidelines and Literature Review | journal = Journal of Clinical Medicine Research | volume = 8 | issue = 4 | pages = 277–83 | date = April 2016 | pmid = 26985247 | pmc = 4780490 | doi = 10.14740/jocmr2456w }}</ref> The use of [[calcium]] in children has been associated with poor neurological function as well as decreased survival.<ref name=":6" /> Correct dosing of medications in children is dependent on weight.<ref name=":6" /> To minimize time spent calculating medication doses, the use of a [[Broselow tape]] is recommended.<ref name=":6" />

The 2010 guidelines from the [[American Heart Association]] no longer contain the recommendation for using atropine in [[pulseless electrical activity]] and [[asystole]] for want of evidence for its use.<ref>{{cite journal | vauthors = Neumar RW, Otto CW, Link MS, Kronick SL, Shuster M, Callaway CW, Kudenchuk PJ, Ornato JP, McNally B, Silvers SM, Passman RS, White RD, Hess EP, Tang W, Davis D, Sinz E, Morrison LJ | title = Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 122 | issue = 18 Suppl 3 | pages = S729-67 | date = November 2010 | pmid = 20956224 | doi = 10.1161/CIRCULATIONAHA.110.970988 | doi-access = free }}</ref><ref name=":3" /> Neither lidocaine nor amiodarone, in those who continue in [[ventricular tachycardia]] or [[ventricular fibrillation]] despite defibrillation, improves survival to hospital discharge but both equally improve survival to hospital admission.<ref>{{cite journal | vauthors = Sanfilippo F, Corredor C, Santonocito C, Panarello G, Arcadipane A, Ristagno G, Pellis T | title = Amiodarone or lidocaine for cardiac arrest: A systematic review and meta-analysis | journal = Resuscitation | volume = 107 | pages = 31–7 | date = October 2016 | pmid = 27496262 | doi = 10.1016/j.resuscitation.2016.07.235 | doi-access = free }}</ref>

<!-- Special cases -->
[[Thrombolytics]] when used generally may cause harm but may be of benefit in those with a confirmed [[pulmonary embolism]] as the cause of arrest.<ref>{{cite journal | vauthors = Perrott J, Henneberry RJ, Zed PJ | s2cid = 11006778 | title = Thrombolytics for cardiac arrest: case report and systematic review of controlled trials | journal = The Annals of Pharmacotherapy | volume = 44 | issue = 12 | pages = 2007–13 | date = December 2010 | pmid = 21119096 | doi = 10.1345/aph.1P364 }}</ref><ref name=Lav2015/> Evidence for use of [[naloxone]] in those with cardiac arrest due to [[opioid]]s is unclear but it may still be used.<ref name=Lav2015/> In those with cardiac arrest due to local anesthetic, [[lipid emulsion]] may be used.<ref name=Lav2015/>

===Targeted temperature management===
Cooling adults after cardiac arrest who have a [[return of spontaneous circulation]] (ROSC) but no return of [[consciousness]] improves outcomes.<ref name=":5">{{cite journal | vauthors = Schenone AL, Cohen A, Patarroyo G, Harper L, Wang X, Shishehbor MH, Menon V, Duggal A | title = Therapeutic hypothermia after cardiac arrest: A systematic review/meta-analysis exploring the impact of expanded criteria and targeted temperature | journal = Resuscitation | volume = 108 | pages = 102–110 | date = November 2016 | pmid = 27521472 | doi = 10.1016/j.resuscitation.2016.07.238 }}</ref><ref name=Arr2016/> This procedure is called [[targeted temperature management]] (previously known as therapeutic hypothermia). People are typically cooled for a 24-hour period, with a target temperature of {{convert|32|-|36|C|F|abbr=}}.<ref name="AHA2015Part132">{{cite journal | vauthors = Neumar RW, Shuster M, Callaway CW, Gent LM, Atkins DL, Bhanji F, Brooks SC, de Caen AR, Donnino MW, Ferrer JM, Kleinman ME, Kronick SL, Lavonas EJ, Link MS, Mancini ME, Morrison LJ, O'Connor RE, Samson RA, Schexnayder SM, Singletary EM, Sinz EH, Travers AH, Wyckoff MH, Hazinski MF | title = Part 1: Executive Summary: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 132 | issue = 18 Suppl 2 | pages = S315-67 | date = November 2015 | pmid = 26472989 | doi = 10.1161/cir.0000000000000252 | doi-access = free }}</ref>  There are a number of methods used to lower the body temperature, such as applying ice packs or cold-water circulating pads directly to the body, or infusing cold saline. This is followed by gradual rewarming over the next 12 to 24 hrs.<ref>{{cite book|title=Therapeutic hypothermia after cardiac arrest : clinical application and management|date=2012|publisher=Springer|others=Lundbye, Justin B.|isbn=9781447129509|location=London|oclc=802346256}}</ref>

Recent meta-analysis found that the use of therapeutic hypothermia after out-of-hospital cardiac arrest is associated with improved survival rates and better neurological outcomes.<ref name=":5" />

===Do not resuscitate===
Some people choose to avoid aggressive measures at the end of life. A [[do not resuscitate]] order (DNR) in the form of an [[advance health care directive]] makes it clear that in the event of cardiac arrest, the person does not wish to receive [[cardiopulmonary resuscitation]].<ref>{{cite journal | vauthors = Loertscher L, Reed DA, Bannon MP, Mueller PS | title = Cardiopulmonary resuscitation and do-not-resuscitate orders: a guide for clinicians | journal = The American Journal of Medicine | volume = 123 | issue = 1 | pages = 4–9 | date = January 2010 | pmid = 20102982 | doi = 10.1016/j.amjmed.2009.05.029 }}</ref> Other directives may be made to stipulate the desire for [[intubation]] in the event of [[respiratory failure]] or, if comfort measures are all that are desired, by stipulating that healthcare providers should "allow natural death".<ref>{{cite journal | vauthors = Knox C, Vereb JA | title = Allow natural death: a more humane approach to discussing end-of-life directives | journal = Journal of Emergency Nursing | volume = 31 | issue = 6 | pages = 560–1 | date = December 2005 | pmid = 16308044 | doi = 10.1016/j.jen.2005.06.020 }}</ref>

===Chain of survival===
Several organizations promote the idea of a [[chain of survival]].  The chain consists of the following "links":
* Early recognition If possible, recognition of illness before the person develops a cardiac arrest will allow the rescuer to prevent its occurrence. Early recognition that a cardiac arrest has occurred is key to survival for every minute a patient stays in cardiac arrest, their chances of survival drop by roughly 10%.<ref name="RCUK2005"/>
* Early CPR improves the flow of blood and of oxygen to vital organs, an essential component of treating a cardiac arrest. In particular, by keeping the brain supplied with oxygenated blood, chances of neurological damage are decreased.
* Early defibrillation is effective for the management of [[ventricular fibrillation]] and pulseless [[ventricular tachycardia]]<ref name = "RCUK2005"/>
* Early advanced care 
* Early post-resuscitation care which may include [[percutaneous coronary intervention]]<ref>{{cite journal | vauthors = Millin MG, Comer AC, Nable JV, Johnston PV, Lawner BJ, Woltman N, Levy MJ, Seaman KG, Hirshon JM | title = Patients without ST elevation after return of spontaneous circulation may benefit from emergent percutaneous intervention: A systematic review and meta-analysis | journal = Resuscitation | volume = 108 | pages = 54–60 | date = November 2016 | pmid = 27640933 | doi = 10.1016/j.resuscitation.2016.09.004 }}</ref>

If one or more links in the chain are missing or delayed, then the chances of survival drop significantly.

These protocols are often initiated by a [[Code Blue (emergency code)|code blue]], which usually denotes impending or acute onset of cardiac arrest or [[respiratory failure]], although in practice, code blue is often called in less life-threatening situations that require immediate attention from a physician.<ref>{{Cite journal|last1=Eroglu|first1=Serkan E.|last2=Onur|first2=Ozge|last3=Urgan|first3=Oğuz|last4=Denizbasi|first4=Arzu|last5=Akoglu|first5=Haldun|date=2014|title=Blue code: Is it a real emergency?|journal=World Journal of Emergency Medicine|volume=5|issue=1|pages=20–23|doi=10.5847/wjem.j.issn.1920-8642.2014.01.003|issn=1920-8642|pmc=4129865|pmid=25215142}}</ref>

===Other===
Resuscitation with [[extracorporeal membrane oxygenation]] devices has been attempted with better results for in-hospital cardiac arrest (29% survival) than out-of-hospital cardiac arrest (4% survival) in populations selected to benefit most.<ref>{{cite journal | vauthors = Lehot JJ, Long-Him-Nam N, Bastien O | title = [Extracorporeal life support for treating cardiac arrest] | journal = Bulletin de l'Académie Nationale de Médecine | volume = 195 | issue = 9 | pages = 2025–33; discussion 2033–6 | date = December 2011 | pmid = 22930866 | doi = 10.1016/S0001-4079(19)31894-1 }}</ref> [[Cardiac catheterization]] in those who have survived an out-of-hospital cardiac arrest appears to improve outcomes although high quality evidence is lacking.<ref>{{cite journal | vauthors = Camuglia AC, Randhawa VK, Lavi S, Walters DL | title = Cardiac catheterization is associated with superior outcomes for survivors of out of hospital cardiac arrest: review and meta-analysis | journal = Resuscitation | volume = 85 | issue = 11 | pages = 1533–40 | date = November 2014 | pmid = 25195073 | doi = 10.1016/j.resuscitation.2014.08.025 }}</ref> It is recommended that it is done as soon as possible in those who have had a cardiac arrest with [[ST elevation]] due to underlying heart problems.<ref name=AHA2015Part1/>

The [[precordial thump]] may be considered in those with witnessed, monitored, unstable ventricular tachycardia (including pulseless VT) if a defibrillator is not immediately ready for use, but it should not delay CPR and shock delivery or be used in those with unwitnessed out of hospital arrest.<ref>{{cite journal | vauthors = Cave DM, Gazmuri RJ, Otto CW, Nadkarni VM, Cheng A, Brooks SC, Daya M, Sutton RM, Branson R, Hazinski MF | title = Part 7: CPR techniques and devices: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 122 | issue = 18 Suppl 3 | pages = S720-8 | date = November 2010 | pmid = 20956223 | pmc = 3741663 | doi = 10.1161/CIRCULATIONAHA.110.970970 }}</ref>

==Prognosis==
The overall chance of survival among those who have cardiac arrest outside hospital is poor, at 10%.<ref>{{cite journal | vauthors = Benjamin EJ, Blaha MJ, Chiuve SE, Cushman M, Das SR, Deo R, de Ferranti SD, Floyd J, Fornage M, Gillespie C, Isasi CR, Jiménez MC, Jordan LC, Judd SE, Lackland D, Lichtman JH, Lisabeth L, Liu S, Longenecker CT, Mackey RH, Matsushita K, Mozaffarian D, Mussolino ME, Nasir K, Neumar RW, Palaniappan L, Pandey DK, Thiagarajan RR, Reeves MJ, Ritchey M, Rodriguez CJ, Roth GA, Rosamond WD, Sasson C, Towfighi A, Tsao CW, Turner MB, Virani SS, Voeks JH, Willey JZ, Wilkins JT, Wu JH, Alger HM, Wong SS, Muntner P | title = Heart Disease and Stroke Statistics-2017 Update: A Report From the American Heart Association | journal = Circulation | volume = 135 | issue = 10 | pages = e146–e603 | date = March 2017 | pmid = 28122885 | pmc = 5408160 | doi = 10.1161/CIR.0000000000000485 }}</ref><ref>{{cite journal | vauthors = Kusumoto FM, Bailey KR, Chaouki AS, Deshmukh AJ, Gautam S, Kim RJ, Kramer DB, Lambrakos LK, Nasser NH, Sorajja D | title = Systematic Review for the 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death | journal = Circulation | volume = 138 | issue = 13 | pages = e392–e414 | date = September 2018 | pmid = 29084732 | doi = 10.1161/CIR.0000000000000550 | doi-access = free }}</ref> Among those who have an out-of-hospital cardiac arrest, 70% occur at home and their survival rate is 6%.<ref>{{cite book|title=Strategies to Improve Cardiac Arrest Survival: A Time to Act|last=Medicine|first=Institute of|date=2015-06-30|isbn=9780309371995 |doi=10.17226/21723|pmid = 26225413}}</ref><ref>{{cite journal | vauthors = Jollis JG, Granger CB | title = Improving Care of Out-of-Hospital Cardiac Arrest: Next Steps | journal = Circulation | volume = 134 | issue = 25 | pages = 2040–2042 | date = December 2016 | pmid = 27994023 | doi = 10.1161/CIRCULATIONAHA.116.025818 | doi-access = free }}</ref> For those who have an in-hospital cardiac arrest, the survival rate is estimated to be 24%.<ref>{{cite journal | vauthors = Daya MR, Schmicker R, May S, Morrison L |date=2015|title=Current burden of cardiac arrest in the United States: report from the Resuscitation Outcomes Consortium. Paper commissioned by the Committee on the Treatment of Cardiac Arrest: Current Status and Future Directions|url=http://www.nationalacademies.org/hmd/~/media/Files/Report%20Files/2015/ROC.pdf}}</ref> Among children rates of survival are 3 to 16% in North America.<ref name="AHA2015Part122">{{cite journal | vauthors = de Caen AR, Berg MD, Chameides L, Gooden CK, Hickey RW, Scott HF, Sutton RM, Tijssen JA, Topjian A, van der Jagt ÉW, Schexnayder SM, Samson RA | title = Part 12: Pediatric Advanced Life Support: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 132 | issue = 18 Suppl 2 | pages = S526-42 | date = November 2015 | pmid = 26473000 | pmc = 6191296 | doi = 10.1161/cir.0000000000000266 }}</ref> For in hospital cardiac arrest survival to discharge is around 22%.<ref name="AHA2015Part42">{{cite journal | vauthors = Kronick SL, Kurz MC, Lin S, Edelson DP, Berg RA, Billi JE, Cabanas JG, Cone DC, Diercks DB, Foster JJ, Meeks RA, Travers AH, Welsford M | title = Part 4: Systems of Care and Continuous Quality Improvement: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 132 | issue = 18 Suppl 2 | pages = S397-413 | date = November 2015 | pmid = 26472992 | doi = 10.1161/cir.0000000000000258 | s2cid = 10073267 | doi-access = free }}</ref><ref name=":3" /> However, some may have [[neurological injury]] that can range from mild memory problems to coma.<ref name=":3" />

Prognosis is typically assessed 72 hours or more after cardiac arrest.<ref name="AHA2015Part13">{{cite journal | vauthors = Neumar RW, Shuster M, Callaway CW, Gent LM, Atkins DL, Bhanji F, Brooks SC, de Caen AR, Donnino MW, Ferrer JM, Kleinman ME, Kronick SL, Lavonas EJ, Link MS, Mancini ME, Morrison LJ, O'Connor RE, Samson RA, Schexnayder SM, Singletary EM, Sinz EH, Travers AH, Wyckoff MH, Hazinski MF | title = Part 1: Executive Summary: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 132 | issue = 18 Suppl 2 | pages = S315-67 | date = November 2015 | pmid = 26472989 | doi = 10.1161/cir.0000000000000252 | doi-access = free }}</ref> Rates of survival are better in those who someone saw collapse, got bystander CPR, or had either ventricular tachycardia or ventricular fibrillation when assessed.<ref name="Sas20102">{{cite journal | vauthors = Sasson C, Rogers MA, Dahl J, Kellermann AL | title = Predictors of survival from out-of-hospital cardiac arrest: a systematic review and meta-analysis | journal = Circulation: Cardiovascular Quality and Outcomes | volume = 3 | issue = 1 | pages = 63–81 | date = January 2010 | pmid = 20123673 | doi = 10.1161/circoutcomes.109.889576 | doi-access = free }}</ref> Survival among those with Vfib or Vtach is 15 to 23%.<ref name="Sas20102" /> Women are more likely to survive cardiac arrest and leave hospital than men.<ref>{{cite journal | vauthors = Bougouin W, Mustafic H, Marijon E, Murad MH, Dumas F, Barbouttis A, Jabre P, Beganton F, Empana JP, Celermajer DS, Cariou A, Jouven X | title = Gender and survival after sudden cardiac arrest: A systematic review and meta-analysis | journal = Resuscitation | volume = 94 | pages = 55–60 | date = September 2015 | pmid = 26143159 | doi = 10.1016/j.resuscitation.2015.06.018 }}</ref>

A 1997 review found rates of survival to discharge of 14% although different studies varied from 0 to 28%.<ref name="Ballew2">{{cite journal | vauthors = Ballew KA | title = Cardiopulmonary resuscitation | journal = BMJ | volume = 314 | issue = 7092 | pages = 1462–5 | date = May 1997 | pmid = 9167565 | pmc = 2126720 | doi = 10.1136/bmj.314.7092.1462 }}</ref> In those over the age of 70 who have a cardiac arrest while in hospital, survival to hospital discharge is less than 20%.<ref name="Gi20142">{{cite journal | vauthors = van Gijn MS, Frijns D, van de Glind EM, C van Munster B, Hamaker ME | title = The chance of survival and the functional outcome after in-hospital cardiopulmonary resuscitation in older people: a systematic review | journal = Age and Ageing | volume = 43 | issue = 4 | pages = 456–63 | date = July 2014 | pmid = 24760957 | doi = 10.1093/ageing/afu035 | doi-access = free }}</ref> How well these individuals are able to manage after leaving hospital is not clear.<ref name="Gi20142" />

A study of survival rates from out-of-hospital cardiac arrest found that 14.6% of those who had received resuscitation by paramedics survived as far as admission to hospital. Of these, 59% died during admission, half of these within the first 24 hours, while 46% survived until discharge from hospital. This reflects an overall survival following cardiac arrest of 6.8%. Of these 89% had normal brain function or mild neurological disability, 8.5% had moderate impairment, and 2% had major neurological disability. Of those who were discharged from hospital, 70% were still alive four years later.<ref name="Cobbe2">{{cite journal | vauthors = Cobbe SM, Dalziel K, Ford I, Marsden AK | title = Survival of 1476 patients initially resuscitated from out of hospital cardiac arrest | journal = BMJ | volume = 312 | issue = 7047 | pages = 1633–7 | date = June 1996 | pmid = 8664715 | pmc = 2351362 | doi = 10.1136/bmj.312.7047.1633 }}</ref>

==Epidemiology==
Based on death certificates, sudden cardiac death accounts for about 15% of all deaths in Western countries.<ref name=Circ01>{{cite journal | vauthors = Zheng ZJ, Croft JB, Giles WH, Mensah GA | title = Sudden cardiac death in the United States, 1989 to 1998 | journal = Circulation | volume = 104 | issue = 18 | pages = 2158–63 | date = October 2001 | pmid = 11684624 | doi = 10.1161/hc4301.098254 | doi-access = free }}</ref> In the United States 326,000 cases of out of hospital and 209,000 cases of in hospital cardiac arrest occur among adults a year.<ref name=AHA2015Part4/><ref name=":3" /> The lifetime risk is three times greater in men (12.3%) than women (4.2%) based on analysis of the [[Framingham Heart Study]].<ref>{{cite web |url=http://circ.ahajournals.org/cgi/content/meeting_abstract/120/18_MeetingAbstracts/S416-c?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=lloyd-jones&searchid=1&FIRSTINDEX=10&sortspec=date&resourcetype=HWCIT |archive-url=https://web.archive.org/web/20110608182635/http://circ.ahajournals.org/cgi/content/meeting_abstract/120/18_MeetingAbstracts/S416-c?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=lloyd-jones&searchid=1&FIRSTINDEX=10&sortspec=date&resourcetype=HWCIT |url-status=dead |archive-date=2011-06-08 |title=Abstract 969: Lifetime Risk for Sudden Cardiac Death at Selected Index Ages and by Risk Factor Strata and Race: Cardiovascular Lifetime Risk Pooling Project – Lloyd-Jones et al. 120 (10018): S416 – Circulation }}</ref>  However this gender difference disappeared beyond 85 years of age.<ref name=Circ01/> Around half of these individuals are younger than 65 years of age.<ref name=":3" />

In the United States during pregnancy cardiac arrest occurs in about one in twelve thousand deliveries or 1.8 per 10,000 live births.<ref name=Lav2015/> Rates are lower in Canada.<ref name=Lav2015>{{cite journal | vauthors = Lavonas EJ, Drennan IR, Gabrielli A, Heffner AC, Hoyte CO, Orkin AM, Sawyer KN, Donnino MW | title = Part 10: Special Circumstances of Resuscitation: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care | journal = Circulation | volume = 132 | issue = 18 Suppl 2 | pages = S501-18 | date = November 2015 | pmid = 26472998 | doi = 10.1161/cir.0000000000000264 | doi-access = free }}</ref>

==Society and culture==
===Names===
In many publications the stated or implicit meaning of "sudden cardiac death" is sudden [[death]] from cardiac causes.<ref name="Dorlands">{{Citation |author=Elsevier |author-link=Elsevier |title=Dorland's Illustrated Medical Dictionary |publisher=Elsevier |url=http://dorlands.com/ |postscript=.}}</ref> However, sometimes physicians call cardiac arrest "sudden cardiac death" even if the person survives. Thus one can hear mentions of "prior episodes of sudden cardiac death" in a living person.<ref name="pmid_18513397">{{cite journal | vauthors = Porter I, Vacek J | title = Single ventricle with persistent truncus arteriosus as two rare entities in an adult patient: a case report | journal = Journal of Medical Case Reports | volume = 2 | pages = 184 | date = May 2008 | pmid = 18513397 | pmc = 2424060 | doi = 10.1186/1752-1947-2-184 }}</ref>

In 2006 the American Heart Association presented the following definitions of sudden cardiac arrest and sudden cardiac death: "Cardiac arrest is the sudden cessation of cardiac activity so that the victim becomes unresponsive, with no normal breathing and no signs of circulation. If corrective measures are not taken rapidly, this condition progresses to sudden death. Cardiac arrest should be used to signify an event as described above, that is reversed, usually by CPR and/or defibrillation or cardioversion, or cardiac pacing. Sudden cardiac death should not be used to describe events that are not fatal".<ref>{{cite journal | vauthors = Buxton AE, Calkins H, Callans DJ, DiMarco JP, Fisher JD, Greene HL, Haines DE, Hayes DL, Heidenreich PA, Miller JM, Poppas A, Prystowsky EN, Schoenfeld MH, Zimetbaum PJ, Heidenreich PA, Goff DC, Grover FL, Malenka DJ, Peterson ED, Radford MJ, Redberg RF | title = ACC/AHA/HRS 2006 key data elements and definitions for electrophysiological studies and procedures: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards (ACC/AHA/HRS Writing Committee to Develop Data Standards on Electrophysiology) | journal = Journal of the American College of Cardiology | volume = 48 | issue = 11 | pages = 2360–96 | date = December 2006 | pmid = 17161282 | doi = 10.1016/j.jacc.2006.09.020 }}</ref>

===Slow code===
In some medical facilities, the resuscitation team may purposely respond slowly to a person in cardiac arrest, a practice known as "[[slow code]]", or may fake the response altogether for the sake of the person's family, a practice known as "show code".<ref>{{cite news|url=https://www.nytimes.com/1987/08/22/opinion/slow-codes-show-codes-and-death.html|title=Slow Codes, Show Codes and Death|newspaper=[[The New York Times]] |publisher=The New York Times Company|date=22 August 1987|access-date=2013-04-06|url-status=live|archive-url=https://web.archive.org/web/20130518042545/http://www.nytimes.com/1987/08/22/opinion/slow-codes-show-codes-and-death.html|archive-date=18 May 2013}}</ref> This is generally done for people for whom performing CPR will have no medical benefit.<ref>{{cite web|url=http://www.cpso.on.ca/policies/policies/default.aspx?ID=1582|title=Decision-making for the End of Life|others=Physician Advisory Service|publisher=[[College of Physicians and Surgeons of Ontario]]|date=May 2006|access-date=2013-04-06|url-status=live|archive-url=https://web.archive.org/web/20130509161003/http://www.cpso.on.ca/policies/policies/default.aspx?ID=1582|archive-date=2013-05-09}}</ref> Such practices are ethically controversial,<ref>{{cite journal | vauthors = DePalma JA, Ozanich E, Miller S, Yancich LM | title = "Slow" code: perspectives of a physician and critical care nurse | journal = Critical Care Nursing Quarterly | volume = 22 | issue = 3 | pages = 89–97 | date = November 1999 | pmid = 10646457 | url = http://www.nursingcenter.com/lnc/journalarticle?Article_ID=437848 | publisher = [[Lippincott Williams and Wilkins]] | url-status = dead | archive-url = https://web.archive.org/web/20130328192748/http://www.nursingcenter.com/lnc/journalarticle?Article_ID=437848 | archive-date = 2013-03-28 | doi = 10.1097/00002727-199911000-00014 | access-date = 2013-04-07 }}</ref> and are banned in some jurisdictions.

== References ==
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== External links ==
{{Medical condition classification and resources
| DiseasesDB      = 2095
| ICD10           = {{ICD10|I|46||i|30}}
| ICD9            = {{ICD9|427.5}}
| ICDO            = 
| OMIM            = 
| MedlinePlus     = 
| eMedicineSubj   = 
| eMedicineTopic  = 
| MeshID          = D006323
| SNOMED CT       = 410429000
}}
{{sisterlinks|display=Cardiac arrest}}
* [http://www.med.upenn.edu/resuscitation/ The Center for Resuscitation Science at the Hospital of the University of Pennsylvania]

{{Circulatory system pathology}}
{{Authority control}}

{{DEFAULTSORT:Cardiac Arrest}}
[[Category:Cardiac arrhythmia]]
[[Category:Medical emergencies]]
[[Category:Causes of death]]
[[Category:Wikipedia medicine articles ready to translate]]
[[Category:RTTEM]]