When viewing this topic in a different language, you may notice some differences in the way the content is structured, but it still reflects the latest evidence-based guidance.

Cardiac arrest

Evidence last reviewed: 30 Sep 2026
Topic last updated: 20 Oct 2026

Summary

Definition

History and exam

Key diagnostic factors

  • patient unresponsive
  • absence of normal breathing
  • absence of circulation
  • cardiac rhythm disturbance
Full details

Risk factors

  • coronary artery disease (CAD
  • left ventricular dysfunction
  • age
  • hypertrophic cardiomyopathy (HCM)
  • arrhythmogenic right ventricular dysplasia (ARVD)
  • long QT syndrome (LQTS)
  • use of drugs that prolong the QT interval or cause electrolyte disturbances
  • acute medical or surgical emergency
  • poisoning
  • Brugada syndrome
  • valvular heart disease
  • smoking
  • history of eating disorders
Full details

Diagnostic tests

1st tests to order

  • continuous cardiac monitoring
  • CBC
  • serum electrolytes
  • ABG
  • cardiac biomarkers
  • point of care ultrasound (POCUS)
Full details

Tests to consider

  • ECG
  • coronary angiography
  • echocardiogram
  • exercise stress testing
  • chest x-ray
  • toxicology screen
  • cardiac magnetic resonance imaging
  • coronary computed tomography angiography
  • signal-averaged ECG (SAECG)
  • electrophysiologic study
Full details

Treatment algorithm

INITIAL

unwitnessed cardiac arrest

ACUTE

shockable rhythms (pulseless ventricular tachycardia or ventricular fibrillation)

nonshockable rhythms (pulseless electrical activity or asystole)

ONGOING

return of spontaneous circulation

no return of spontaneous circulation

Contributors

Authors

John Wink, MD

Emergency Physician

Alberta Health Services

Alberta

Canada

Disclosures

JW declares that he has no competing interests.

Eddy Lang, MD

Professor and Department Head of Emergency Medicine

Cumming School of Medicine

University of Calgary

Alberta Health Services

Calgary

Canada

Disclosures

EL declares that he has no competing interests.

Antonio Abbate, MD, PhD

Ruth C. Heede Professor of Cardiovascular Medicine

Division of Cardiovascular Medicine

Berne Cardiovascular Research Center

University of Virginia School of Medicine

Charlottesville, VA

Disclosures

AA has received consultant fees from Kiniksa Pharmaceuticals. He is an author of references cited in this topic.

Acknowledgements

Dr John Wink and Professor Eddy Lang would like to gratefully acknowledge Dr Amar Krishnaswamy and Dr Arman T. Askari, previous contributors to this topic.

Disclosures

AK and ATA declare that they have no competing interests.

Peer reviewers

Anthony Aizer, MD, MS

Instructor

NYU Department of Medicine (Cardiology)

Leon H Charney Heart Rhythm Center and New York University

New York, NY

Disclosures

AA declares that he has no competing interests.

Massimo F. Piepoli, MD, PhD, FESC

Honorary Clinical Senior Lecturer/Consultant

Department of Cardiology

Imperial College London

London

UK

Disclosures

MFP declares that he has no competing interests.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Zeppenfeld K, Tfelt-Hansen J, de Riva M, et al. 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J. 2022 Oct 21;43(40):3997-4126.Full text  Abstract

Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Circulation. 2018 Sep 25;138(13):e272-391.Full text  Abstract

Greif R, Bray JE, Djärv T, et al. 2024 International consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations: summary from the basic life support; advanced life support; pediatric life support; neonatal life support; education, implementation, and teams; and first aid task forces. Resuscitation. 2024 Dec;205:110414.Full text  Abstract

Nolan JP, Sandroni C, Böttiger BW, et al. European Resuscitation Council and European Society of Intensive Care Medicine guidelines 2021: post-resuscitation care. Intensive Care Med. 2021 Apr;47(4):369-421.Full text  Abstract

Del Rios M, Bartos JA, Panchal AR, et al. Part 1: executive summary: 2025 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2025 Oct 21;152(16_suppl_2):S284-312.Full text  Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.
  • Cardiac arrest images
  • Guidelines

    • Part 1: executive summary: 2025 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care
    • 2024 International consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations
    More Guidelines
  • Patient information

    Heart attack: what is it?

    Bag-valve-mask ventilation

    More Patient information
  • Videos

    Radial artery puncture animated demonstration

    Femoral artery puncture animated demonstration

    More videos
  • padlock-lockedLog in or subscribe to access all of BMJ Best Practice

Use of this content is subject to our disclaimer