Low diagnostic yield of electrocardiogram testing in younger patients with syncope

Routine ECG testing is recommended in the evaluation of syncope, although the value of such testing in young patients is unclear. For ECG testing, we assess the diagnostic yield (frequency that ECG identified the reason for syncope) and predictive accuracy for 14-day cardiac events after an episode of syncope as a function of age.

Adult patients with syncope or near-syncope were prospectively enrolled for 1 year at a single academic emergency department (ED). A 3-physician panel reviewed ED charts, hospital records, and telephone interview forms to identify predefined cardiac events. The primary outcome included all 14-day, predefined cardiac events including arrhythmia, myocardial ischemia, and structural heart disease.

Of 592 eligible patients, 477 (81%) provided informed consent. Direct telephone contact or admission/outpatient records were successfully obtained for 461 (97%) patients, who comprised the analytic cohort. There were 44 (10%) patients who experienced a 14-day cardiac event. Overall diagnostic yield of ECG testing was 4% (95% confidence interval 2% to 6%). For patients younger than 40 years, ECG testing had a diagnostic yield of 0% (95% confidence interval 0% to 3%) and was associated with a 10% frequency of abnormal findings.

ECG testing in patients younger than 40 years did not reveal a cardiac cause of syncope and was associated with a significant frequency of abnormal ECG findings unrelated to syncope. Although our findings should be verified in larger studies, it may be reasonable to defer ECG testing in younger patients who have a presentation consistent with a benign cause of syncope.