Last reviewed: 6 Nov 2021
Last updated: 24 Aug 2018



History and exam

Other diagnostic factors

  • low risk for adverse outcomes
  • hx of recurrent faints
  • provocative factor
  • nausea
  • lightheadedness
  • pallor
  • diaphoresis
  • diminished vision or hearing
  • physical injury
  • fatigue after episode
  • palpitations
  • bradycardia
  • absence of FHx of sudden death
  • neuralgia

Risk factors

  • prior syncope
  • prior history of arrhythmias, myocardial infarction, heart failure, or cardiomyopathy
  • severe aortic stenosis
  • prolonged standing
  • emotional stress (especially in a warm, crowded environment)
  • dehydration/hypovolaemia
  • preceding episode of nausea and/or vomiting
  • preceding episode of severe pain

Diagnostic investigations

1st investigations to order

  • 12-lead ECG
  • serum haemoglobin
  • plasma blood glucose
  • serum beta-human chorionic gonadotrophin
  • cardiac enzymes
  • D-dimer level
  • serum cortisol
  • urea or serum creatinine

Investigations to consider

  • echocardiogram
  • tilt-table test
  • carotid sinus massage (CSM)
  • insertable loop recorder
  • electrophysiological study
  • Valsalva manoeuvre
  • active standing test
  • cold pressor test
  • cough test

Emerging tests

  • adenosine triphosphate (ATP) test

Treatment algorithm



Bryant Lin, MD
Bryant Lin

Clinical Assistant Professor of Medicine

Division of Primary Care and Population Health

Stanford University School of Medicine




BL declares that he has no competing interests.

Paul J. Wang, MD, FACC, FHRS
Paul J. Wang

Professor of Medicine

Stanford Arrhythmia Service

Stanford University School of Medicine




PJW receives fellowship support, honoraria, and clinical trial support from Medtronic, which manufactures LINQ, an implantable loop recorder.


Dr Bryant Lin and Dr Paul J. Wang would like to gratefully acknowledge Dr David G. Benditt and Dr John T. Nguyen, previous contributors to this monograph. DGB has consultant and equity positions: Medtronic Inc., St Jude Medical Inc., Transoma Inc., Cardionet Inc. DGB is also an author of several references cited in this monograph. JTN declares that he has no competing interests.

Peer reviewers

Sanjiv Petkar, MBBS, MD, DM (Cardiology), MRCP

Consultant Cardiologist

Hull and East Riding of Yorkshire NHS Trust

Castle Hill Hospital

East Yorkshire



SP has received sponsorship in the past from Medtronic, Inc. and St Jude Medical, Inc. for attending conferences. He has received speaker's fees from Medtronic, Inc. In addition, he was in receipt of a research grant from Medtronic, Inc. to the University of Manchester.

Kenneth A. Ellenbogen, MD

Kontos Professor of Cardiology

Medical College of Virginia




KAE declares that he has no competing interests.

Andrew Parfitt, MBBS, FFAEM

Clinical Director

Acute Medicine

Associate Medical Director

Consultant Emergency Medicine

Guy's and St Thomas' NHS Foundation Trust

Clinical Lead and Consultant

Accident Emergency Medicine

St Thomas' Hospital




AP declares that he has no competing interests.

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