Last reviewed:October 2019
Last updated:April  2018



History and exam

Key diagnostic factors

  • family history of sudden cardiac arrest
  • pulmonary disease
  • chest pain
  • palpitations
  • syncope
  • presence of other risk factors
  • medications which prolong the QT interval or cause electrolyte disturbances
  • illicit substances
  • trauma

Other diagnostic factors

  • hypertension
  • hypercholesterolemia
  • diabetes mellitus
  • kidney disease
  • family history of coronary artery disease
  • valvular heart disease
  • elevated jugular venous pulse
  • heart murmur
  • abnormalities on auscultation of lungs
  • tracheal deviation
  • neurologic deficits
  • history of eating disorders

Risk factors

  • coronary artery disease (CAD)
  • left ventricular dysfunction
  • hypertrophic cardiomyopathy (HCM)
  • arrhythmogenic right ventricular dysplasia (ARVD)
  • long QT syndrome (LQTS)
  • acute medical or surgical emergency
  • Brugada syndrome
  • smoking

Diagnostic investigations

1st investigations to order

  • ECG
  • CBC
  • basic metabolic panel
  • ABG
  • cardiac biomarkers
  • toxicology screen
  • CXR
  • echocardiogram
  • coronary angiography
Full details

Investigations to consider

  • cardiac magnetic resonance imaging
  • signal-averaged ECG (SAECG)
  • electrophysiologic study
Full details

Treatment algorithm


Professor and Department Head of Emergency Medicine

Cumming School of Medicine

University of Calgary

Alberta Health Services




EL served as a consultant to the American Heart Association providing methods support using GRADE for cardiac arrest guidelines published in Circulation and Resuscitation in October 2015.

Professor Eddy Lang would like to gratefully acknowledge Dr Amar Krishnaswamy and Dr Arman T. Askari, previous contributors to this topic. AK and ATA declare that they have no competing interests.

Peer reviewersVIEW ALL

Professor of Medicine

Division of Cardiology

University of California

San Francisco



VM declares that he has no competing interests.


NYU Department of Medicine (Cardiology)

Leon H Charney Heart Rhythm Center and New York University

New York



AA declares that he has no competing interests.

Honorary Clinical Senior Lecturer/Consultant

Department of Cardiology

Imperial College London




MFP declares that he has no competing interests.

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