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Think Twice Before Using Pacemaker Therapy for Vasovagal Syncope

This double-blind randomized trial reveals why.

Vasovagal syncope, the most common type of syncope, is characterized by an increase in vagal tone and a drop in sympathetic tone that can lead to hypotension, with or without bradycardia. In 3 previous, unblinded clinical trials, pacemaker therapy seemed to be effective for treating vasovagal syncope (e.g., Journal Watch Cardiology Sep 29 2000).

Now, researchers have conducted a double-blind, randomized, multicenter trial of pacemaker therapy in 100 patients with histories of vasovagal syncope (median number of episodes in the previous year, 4); nearly all had tried drug therapy. All 100 had a positive tilt-table test; 19 exhibited a lowest heart rate (HR) of <40 bpm. Each patient received a dual-chamber pacemaker, with 52 randomized to sensing without pacing (ODO mode) and 48 to dual-chamber pacing in the DDD mode (DDD pacing was initiated upon an abrupt 20-bpm decrease in HR).

Syncope recurred in 42% of the ODO group and 33% of the DDD group within 6 months; the 30% relative risk reduction in time to syncope with DDD pacing was not significant. Pacemaker complications included lead dislodgement or need for repositioning (in 3 ODO patients and 4 DDD patients), subclavian vein thrombosis in 1 (ODO), and pericardial tamponade in 1 (DDD).

Comment: In this double-blind study, pacemaker therapy was no better than placebo for preventing recurrent vasovagal syncope. This finding is important, especially given the expense, complications, and lifelong discomfort associated with pacemakers. Pacemaker therapy should be considered for vasovagal syncope only when other therapeutic options have failed and should be used preferentially in older patients.

— Hugh Calkins, MD

Published in Journal Watch Cardiology June 20, 2003

Citation(s):

Connolly SJ et al. for the VPS II Investigators. Pacemaker therapy for prevention of syncope in patients with recurrent severe vasovagal syncope: Second Vasovagal Pacemaker Study (VPS II): A randomized trial. JAMA 2003 May 7; 289:2224-9.

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