Predictor of a negative tilt-table test result based on early heart rate variation in patients with a history of syncope.

Lack of early sympathetic overreactivity measured by early increase in heart rate has been shown to predict a negative tilt-table (TT) test result. The goal of this study was to evaluate this observation in patients with a history of syncope. The author retrospectively identified 27 patients with a history of syncope undergoing TT testing. The difference between maximal heart rate during the first 10 minutes of the tilting and baseline heart rate was used for early heart rate change. There was a significant association between the probability of a negative TT test result and failure to increase early heart rate over 19 beats per minute. The sensitivity of a negative TT test result was 93.3%, with a specificity of 66.7% (odds ratio, 0.1; confidence interval, 0.14-0.69; P=.001). This study confirms previous findings that failure to increase the heart rate early during a TT test can predict low probability of syncope.