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.

Last reviewed: 16 Mar 2025
Last updated: 24 Nov 2023

Summary

Definition

History and exam

Key diagnostic factors

  • history of coronary artery disease
  • history of hypertrophic cardiomyopathy
  • history of idiopathic dilated cardiomyopathy
  • presence of other risk factors
  • asymptomatic presentation
  • tachycardia

Other diagnostic factors

  • palpitations
  • dizziness
  • lightheadedness
  • pre-syncope
  • syncope

Risk factors

  • coronary artery disease
  • left ventricular systolic dysfunction
  • hypertrophic cardiomyopathy
  • idiopathic dilated cardiomyopathy
  • long QT syndrome
  • Brugada's syndrome
  • electrolyte imbalance
  • drug toxicity
  • Chagas' disease and other cardiomyopathies
  • sleep-disordered breathing
  • catecholaminergic polymorphic VT
  • family history of sudden death
  • mental or physical stress

Diagnostic investigations

1st investigations to order

  • ECG
  • electrolyte panel
  • troponin
  • CK-MB

Investigations to consider

  • 24-hour ambulatory ECG monitoring
  • echocardiogram
  • cardiac catheterisation
  • cardiac MRI with gadolinium
  • electrophysiological testing
  • stress testing
  • genetic screening

Treatment algorithm

Contributors

Authors

Fred Kusumoto, MD
Fred Kusumoto

Professor of Medicine

Mayo Medical School

Division of Cardiovascular Diseases

Department of Medicine

Mayo Clinic Florida

Jacksonville

FL

Disclosures

FK declares that he has no competing interests.

Acknowledgements

Professor Kusumoto would like to gratefully acknowledge Dr Ronald R. Butendieck Jr, a previous contributor to this topic.

Disclosures

RRB declares that he has no competing interests.

Peer reviewers

Timothy Markman, MD

Assistant Professor of Medicine

Hospital of the University of Pennsylvania

Philadelphia

PA

Disclosures

TM declares that he has no competing interests.

Vias Markides, MB(Hons), BS(Hons), MD, FRCP

Consultant Cardiologist and Chair

Arrhythmias

Royal Brompton & Harefield NHS Trust

Hon. Senior Lecturer

Imperial College

London

UK

Disclosures

VM declares that he has no competing interests.

Use of this content is subject to our disclaimer