Distinguishing cardiac syncope from vasovagal syncope in a referral population

To identify characteristics that distinguish cardiac from vasovagal syncope.

We compared characteristics of patients ≤18 years of age with vasovagal and cardiac syncope. Vasovagal syncope subjects represented all patients presenting to outpatient cardiology during a 1-year period for initial evaluation of syncope diagnosed with vasovagal syncope. Cardiac patients were all patients identified by review of diagnoses known to include syncope as a symptom who presented with syncope to the emergency department or inpatient or outpatient cardiology during a 10-year period identified with cardiac etiology.

There were 89 patients 4-18 years of age with vasovagal syncope and 17 patients 4 months to 17 years of age with cardiac syncope. When we compared patients with cardiac syncope to those with vasovagal syncope, we found that syncope surrounding activity was present in 65% vs 18% (P < .001), family history of cardiac disease or sudden cardiac death was identified in 41% vs 25% (P = .2), abnormal findings on the physical examination supporting cardiac diagnosis were present in 29% vs 0% (P < .001), and abnormal findings on electrocardiograms were found in 76% vs 0%, respectively (P < .001). Screening for cardiac disease using any 1 of these 4 characteristics had a sensitivity of 100% and specificity of 60%. Using this screening rule, we found that 60% of patients with vasovagal syncope would not have been referred to cardiology.

Cardiac and vasovagal syncope have dramatic differences in presentation. A screening rule that uses historic features, physical examination findings, and electrocardiogram will accurately separate patients requiring further evaluation for cardiac etiology from those with vasovagal syncope in whom cardiology referral is unnecessary.