Stepwise evaluation of unexplained syncope in a large ambulatory population

Area of Science:

• Cardiology
• Neurology

Background:

• Up to 60% of syncope (fainting) episodes are unexplained.
• Standardized diagnostic approaches are crucial for unexplained syncope.

Purpose of the Study:

• To evaluate the effectiveness of a standardized, stepwise diagnostic approach for unexplained syncope in an ambulatory setting.

Main Methods:

• 939 patients with unexplained syncope underwent standardized evaluation.
• Tests included history, physical exam, ECG, head-up tilt testing (HUTT), carotid sinus massage (CSM), and hyperventilation (HYV).
• Echocardiogram, stress tests, electrophysiological studies (EPS), and implantable loop recorders (ILR) were used selectively.

Main Results:

• A cause was identified in 66% of patients.
• Common causes included vasovagal (27%), psychogenic (14%), arrhythmias (6%), and hypotension (6%).
• Noninvasive tests identified 92% of causes; HUTT (38%), CSM (28%), HYV (49%), EPS (22%), ILR (56%).

Conclusions:

• A standardized, stepwise evaluation successfully identified causes in two-thirds of unexplained syncope cases.
• Neurally mediated and psychogenic syncope were the most frequent diagnoses.
• Cardiac arrhythmias were an uncommon cause, but sudden syncope in older patients with limitations or prolonged P-wave warrants investigation for arrhythmias.