Two year follow-up in 643 patientswith non-invasively unexplained syncope and therapy guided byelectrophysiologic study

Aim:Although it has become standard practice to perform electrophysiologic studies in patients with unexplained syncope, limited information exists on prognosis after therapy guided by electrophysiologic studies.Methods and results:Electrophysiologic studies were performed in 643 patients with unexplained syncope. Electrophysiologic studies revealed conduction abnormalities and tachyarrhythmias accounting for syncope in 35% of patients. An ejection fraction ≤ 40%, a PR-interval > 2 s and injury are helpful parameters in predicting a positive electrophysiologic study. There was no difference regarding cumulative 2-year survival rate after therapy guided by positive electrophysiologic study compared to patients with negative electrophysiologic study. The cumulative 2-year survival free-of-syncope rate was significantly higher after therapy guided by electrophysiologic study compared to patients with negative electrophysiologic findings—for patients with organic heart disease (71.3% vs 48.5%, p < 0.001) and patients without disease (91.3% vs. 65.2%, p < 0.001). Using a logistic regression model, a positive electrophysiologic study was associated with a favorable outcome; multiple syncopal events or organic heart disease were associated with an unfavorable outcome.Conclusion:The cumulative overall 2-year surival free-of-syncope rate is significantly higher in patients after therapy guided by electrophysiologic study compared to patients with negative electrophysiologic findings.