Dual-chamber pacing in the treatment of neurally mediated tilt-positive cardioinhibitory syncope pacemaker - Versus no therapy: A multicenter randomized study

Background-This study was performed to compare implantation of a DDI pacema ker with rate hysteresis with no implant in respect to syncopal recurrences in patients with severe cardioinhibitory tilt-positive neurally mediated s yncope. Methods and Results-Forty-two patients from 18 European centers were random ized to receive a DDI pacemaker programmed to 80 bpm with hysteresis of 45 bpm (19 patients) or no pacemaker (23 patients). Inclusion criteria were gr eater than or equal to 3 syncopes over the last 2 years and a positive card ioinhibitory (Vasovagal Syncope International Study types 2A and 2B) respon se to tilt testing. The median number of previous syncopal episodes was 6; asystolic response to tilt testing was present in 36 patients (86%) (mean a systole, 13.9 +/- 10.2 seconds). All patients were followed up for a minimu m of 1.0 years and a maximum of 6.7 years (mean, 3.7 +/- 2.2). One patient (5%) in the pacemaker arm experienced recurrence of syncope compared with 1 4 patients (61%) in the no-pacemaker arm (P = 0.0006). In the no-pacemaker arm, the median time to first syncopal recurrence was 5 months, with a rate of 0.44 per year. On repeated tilt testing performed within 15 days after enrollment, positive responses were observed in 59% of patients with pacema kers and in 61% of patients without pacemakers (P = NS). Conclusions-In a limited, select group of patients with tilt-positive cardi oinhibitory syncope, DDI pacing with hysteresis reduced the likelihood of s yncope. The benefit of the therapy was maintained over the long term. Even in untreated patients, the syncopal recurrence burden was low. A negative r esult of tilt testing was not a useful means to evaluate therapy efficacy.