BACKGROUND: Recent work with head-up tilt-table testing has suggested that many patients with syncope may have recurrent neurally mediated episodes of bradycardia, hypotension, or both. The purpose of this study was to determine how to identify patients at high risk of a recurrence of neuromediated syncope after a positive isoproterenol/tilt-table test. METHODS AND RESULTS: A cohort of 101 drug-free patients in a university hospital outpatient clinic with syncope and a positive isoproterenol/tilt-table test underwent baseline assessment of demographic variables, symptomatic burden, and hemodynamic and clinical responses to tilt testing. The primary outcome measure was the time to the first recurrent syncopal spell. The actuarial probabilities of remaining syncope free after 1 and 2 years were 72% and 60%, respectively. Multivariate proportional hazards analysis demonstrated that the most powerful predictor of a recurrence of syncope was the logarithm of the number of preceding syncopal spells (P<.001). Other predictive variables included the duration of syncopal symptoms, tilt test symptomatic outcome, and trough heart rate. The probability of a recurrence of syncope also varied with the logarithm of the frequency of preceding spells (P=.008). The median frequency of pretest spells was 0.3/month; after the tilt test, the median frequency dropped approximately 90% to 0.03 per month. CONCLUSIONS: The risk of a recurrence of syncope after a positive tilt-table test can be predicted with simple pretest and intratest variables.
BACKGROUND: Recent work with head-up tilt-table testing has suggested that many patients with syncope may have recurrent neurally mediated episodes of bradycardia, hypotension, or both. The purpose of this study was to determine how to identify patients at high risk of a recurrence of neuromediated syncope after a positive isoproterenol/tilt-table test. METHODS AND RESULTS: A cohort of 101 drug-free patients in a university hospital outpatient clinic with syncope and a positive isoproterenol/tilt-table test underwent baseline assessment of demographic variables, symptomatic burden, and hemodynamic and clinical responses to tilt testing. The primary outcome measure was the time to the first recurrent syncopal spell. The actuarial probabilities of remaining syncope free after 1 and 2 years were 72% and 60%, respectively. Multivariate proportional hazards analysis demonstrated that the most powerful predictor of a recurrence of syncope was the logarithm of the number of preceding syncopal spells (P<.001). Other predictive variables included the duration of syncopal symptoms, tilt test symptomatic outcome, and trough heart rate. The probability of a recurrence of syncope also varied with the logarithm of the frequency of preceding spells (P=.008). The median frequency of pretest spells was 0.3/month; after the tilt test, the median frequency dropped approximately 90% to 0.03 per month. CONCLUSIONS: The risk of a recurrence of syncope after a positive tilt-table test can be predicted with simple pretest and intratest variables.