Repeated tilt testing in patients with tilt-positive neurally mediated syncope

In this study we have included 222 patients with apparent neurally mediated syncope and with a positive diagnostic tilt test. The mean age was 33.4+/-21.2 years (median 25.3): there were 107 men (median age 25.3) and 115 women (median age 22.6). The age difference between males and females was statistically significant (P = 0.002). The response to the diagnostic tilt test was: type 1 (mixed) in 74 patients; type 2A (cardioinhibitory and bradycardia) in 6; type 2B (cardioinhibitory and asystole) in 61; type 3 (vasodepressor) in 81. In all 222 patients the diagnostic tilt test was positive after 19+/-11 min (mean+/-SD), median time: 18 min. For the four types of syncope, the duration in minutes of the diagnostic tilt test was: type 1 (mixed) 19.5+/-11.4; type 2A (cardioinhibitory) 24.8+/-13.6; type 2B (cardioinhibitory and asystole) 14.7+/-10.2; type 3 (vasodepressor) 21.6+/-11.1. A significant difference was found between type 2B and type 3 responses (P = 0.002). Between males and females no significant differences in the duration of the diagnostic tilt test were found, neither for all responses, nor for the four subtypes. A type 2B (cardioinhibitory and asystole) response occurred in 61 patients. The duration of asystole was 12.8+/-10.6s (mean+/-SD; median 9, minimum 3, maximum 60). The head-up tilt test was repeated day after day: one session per day. The response became negative at the second session in 119 patients (54%); at session 3 in 47 (21%); at session 4 in 30 (13%); at session 5 in 15 (7%); at session 6 in 6 (3%); at session 7 in 2 (1%); at session 8 in 3 (1%). For all 222 patients the mean number of sessions in order to obtain a negative tilt test was 2.9 (SD 1.3; median 2). Only 25% of patients remained tilt-positive for three or more sessions. A negative tilt test was ultimately obtained in every patient. Follow-up data are available for 202/222 patients. The time span between the first and last tilt test was 11.1+/-10 months (median 8.8). Of these 202 patients, 163 remained free of any event (80.7%).