Diagnostic value of history in patients with syncope with or without heart disease

OBJECTIVES We sought to establish what historical findings are predictive of the cause of syncope. BACKGROUND The clinical features of the various types of syncope have not been systematically investigated. METHODS Three hundred forty-one patients with syncope were prospectively evaluated. Each patient was interviewed using a standard questionnaire. A cause of syncope was assigned using standardized diagnostic criteria. RESULTS A cardiac cause of syncope was established in 23% of the patients, a neurally mediated cause in 58% and a neurologic or psychiatric cause in 1%, and in the remaining 18%, the cause of syncope remained unexplained. In a preliminary analysis including age, gender and the presence of suspected or certain heart disease after the initial evaluation, only heart disease was an independent predictor of a cardiac cause of syncope (odds ratio 16, P = 0.00001), with a sensitivity of 95% and a specificity of 45%. In contrast, the absence of heart disease allowed us to exclude a cardiac cause of syncope in 97% of the patients. In patients with certain or suspected heart disease, the most specific predictors of a cardiac cause were syncope in the supine position or during effort, blurred vision and convulsive syncope. Significant and specific predictors of a neurally mediated cause were time between the first and last syncopal episode >4 years, abdominal discomfort before the loss of consciousness and nausea and diaphoresis during the recovery phase. In the patients without heart disease, palpitation was the only significant predictor of a cardiac cause. CONCLUSIONS The presence of suspected or certain heart disease after the initial evaluation is a strong predictor of a cardiac cause of syncope. A few historical findings are useful to predict cardiac and neurally mediated syncope in patients with and without heart disease.