Diagnostic Approach to Syncope

Initial Evaluation

The American College of Cardiology/American Heart Association (ACC/AHA) recommends that a 12-lead ECG should be performed immediately as the initial diagnostic test for patients presenting with syncope, regardless of the suspected etiology, as it can reveal potentially life-threatening but treatable cardiac disorders 1, 2, 3.
All patients with transient loss of consciousness (syncope) must receive a 12-lead ECG, as it is a low-cost test that can reveal potentially life-threatening cardiac disorders 1, 3.
The ACC/AHA specifically recommends that a detailed medical history, physical examination, family history, and a 12-lead ECG should be performed in all pediatric patients presenting with syncope 2.

Emotional triggers, such as argument, can be associated with long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT), both potentially fatal but treatable conditions 2, 6.
Family history of sudden cardiac death must be sought, as this significantly increases the risk of inherited arrhythmia syndromes 2, 6.

The 12-lead ECG can identify QT prolongation, suggesting LQTS, which causes syncope with emotional triggers and carries a risk of sudden death 1, 2, 5.
The ECG can also detect conduction abnormalities (AV block, bundle branch blocks) that may progress to life-threatening arrhythmias 5.
Pre-excitation patterns (Wolff-Parkinson-White syndrome), Brugada pattern, or signs of arrhythmogenic right ventricular cardiomyopathy can also be identified on the ECG 2.
Evidence of hypertrophic cardiomyopathy (left ventricular hypertrophy patterns) can be detected on the ECG 2, 4.

Do not assume vasovagal syncope without obtaining an ECG, even when the history seems typical, as approximately 1.5% to 6% of pediatric syncope cases have a cardiac etiology that can cause sudden death 2.
Do not mistake convulsive syncope for epilepsy, as the brief, unilateral twitching with rapid recovery is characteristic of anoxic seizure activity from syncope, not a primary seizure disorder requiring EEG 1, 3.
Do not order echocardiography before ECG, as the ECG guides whether structural imaging is needed and is far more cost-effective as the initial test 1, 3, 4.