Timing of first recurrence of syncope predicts syncopal frequency after a positive tilt table test result

Abstract

Objectives. This study sought to determine whether the time to first recurrence of syncope after a positive isoproterenol-tilt table test result accurately predicts the eventual frequency of syncope. Background. Both patient care and future clinical trials involving patients with neuromediated syncope will require a simple measure that reflects the frequency of syncope. The time from tilt table testing to the first recurrence of syncope might be such a measure. Methods. A cohort of 46 patients with syncope, in a university outpatient clinic, who had at least one syncopal spell after a positive isoproterenol-tilt table test result were followed up for up to 6.5 years (mean [±SD] 48 ± 14 months). The time from tilt table testing to the first recurrence of syncope was correlated. Results. A total of 40 of 46 patients had more than one recurrent spell, with a median of eight recurrent spells. The time to the first syncopal spell predicted the frequency of spells with r = -0.79 (p < 0.001), whereas the time to the second spell predicted the frequency with r = -0.92 (p < 0.001). Patients who fainted within 1 month of tilt testing had a geometric mean frequency of 1.35 spells/month (95% confidence limits 0.49, 3.74) compared with patients who fainted 1 to 24 months after testing (0.12 spells/month; 95% confidence limits 0.07 to 0.18, p < 0.001). Finally, the frequency of syncopal spells bore no relation to the duration of follow-up. Conclusions. The time to the first recurrent spell predicts the frequency of syncopal spells after a positive tilt table test result, and the instantaneous risk of syncope is constant.