Usefulness of a non-invasive scoring system in predicting the outcome of electrophysiologic studies in non-invasively unexplained syncope.

BACKGROUND: An electrophysiologic study is a useful method to clarify the cause of non-invasively unexplained syncope in 18-60% of patients. However, it is invasive with possible procedure-related complications. Therefore, it would be helpful to identify patients in whom an electrophysiologic study is useful for diagnosis of syncope. METHODS: Patients with unexplained syncope were prospectively enrolled in a registry, if an electrophysiologic study was performed. The study group comprised of 643 consecutive patients. RESULTS: The electrophysiologic study revealed conduction abnormalities and tachyarrhythmias accounting for syncope in 35% of patients. Using a logistic regression model, history of injury during syncope (p<0.001), ejection fraction < or =40% (p=0.03), and PR interval >0.2 s (p=0.001) were independent predictors of an abnormal electrophysiologic study. These three clinical and easily measurable variables were entered into a scoring system. The maximal score consisted of 3 points. A score of >1 predicts a positive electrophysiologic study result in more than 70% of patients with non-invasively unexplained syncope. CONCLUSION: Electrophysiologic abnormalities were detected in 35% of patients with unexplained syncope. A history of injury, ejection fraction < or =40% and a PR interval >200 ms were independent predictors for a positive electrophysiologic study.