Syncope and Structural Heart Disease: Historical Criteria for Vasovagal Syncope and Ventricular Tachycardia

INTRODUCTION: to develop evidence-based criteria that distinguish syncope due to ventricular tachycardia (VT) from vasovagal syncope (VVS) in patients with structural heart disease (SHD). METHODS AND RESULTS: one hundred and thirty-four patients with syncope and SHD completed a 118-item questionnaire and underwent noninvasive and invasive diagnostic assessments in a prospective cohort study. The contributions of symptoms to diagnoses were estimated with logistic regression and a point score was developed and then tested using receiver-operator characteristic analysis. The effectiveness of the decision rule was evaluated with long-term outcome. There were 21 patients with tilt-positive VVS, 78 with clinically declared or inducible VT, and 35 with no identified cause of syncope. Six features were significant predictors. Factors that predicted VT included male sex and age at onset >35 years; factors predicting VVS included prolonged sitting or standing; developing presyncope preceded by stress; recurrent headaches; and experiencing fatigue, which lasts longer than 1 minute after syncope. The point score correctly classified 92% of patients, diagnosing VT with 99% sensitivity and 68% specificity. The negative predictive value is ≥ 96%. Fully 67% of patients with undiagnosed syncope were classified as having VT based upon their symptoms. The decision rule predicted 9-year arrhythmia-free survival (VVS 84%, VT 39%, hazard ratio 4.32) and 9-year overall survival (VVS 66%, VT 37%, hazard ratio 2.87). CONCLUSIONS: the causes of syncope in patients with SHD, and their clinical outcomes, can be estimated accurately based on the clinical history. The history safely screens out the possibility of VT as a cause of syncope.