The North American Vasovagal Pacemaker Study (VPS) - A randomized trial ofpermanent cardiac pacing for the prevention of vasovagal syncope

Objectives. This study was done to evaluate pacemaker therapy for severe re current vasovagal syncope, Background. Nonrandomized studies have suggested that permanent pacing migh t help control the symptoms of recurrent vasovagal syncope, The study goal was to evaluate the effect of permanent pacemaker implantation on syncope i n patients with frequently recurrent vasovagal syncope, Methods. Patients,vith greater than or equal to 6 lifetime episodes of sync ope and,vith a tilt-table test that induced syncope or presyncope, as well as a relative bradycardia, were randomized to receive a dual-chamber pacema ker or not. The pacemaker prevented bradycardia and provided high-rate paci ng if a predetermined drop in heart rate occurred (rate-drop response). The primary outcome was the first recurrence of syncope. Patients also complet ed a detailed diary recording presyncopal episodes. Results. A total of 284 patients was originally planned and a pilot study o f 60 patients was initiated. At the planned first formal interim analysis o f efficacy of the pilot study, an unanticipated large treatment effect was observed which fulfilled the prespecified criteria for early termination of the study, At that time, there were 54 patients enrolled, randomized evenl y to no pacemaker or to pacemaker. In the no pacemaker and pacemaker groups the mean ages were 40 and 46 years; 74% and 70% patients, respectively, we re female. The baseline tilt-table test showed a slowest heart <60/min or l ongest heart period >1000 ms in 60% of no-pacemaker patients and 72% of pac emaker patients. There was a marked reduction in the postrandomization risk of syncope in pacemaker patients (relative risk reduction 85.4%, 95% confi dence interval 59.7% to 94.7%; 2p = 0.000022), Conclusions. Dual chamber pacing with rate drop response reduces the likeli hood of syncope in patients with recurrent vasovagal syncope, (C) 1998 by t he American College of Cardiology.