Two year follow-up in 643 patients with non-invasively unexplained syncope and therapy guided by electrophysiologic 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 less than or equal to 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.