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Neurally Mediated Syncope -- Are Pacemakers Effective?

Control of bradycardia did not prevent recurrent syncope.

Results of several small, unblinded, randomized studies have suggested that patients with neurally mediated syncope (also known as vasovagal syncope) benefit from pacemaker therapy; however, findings from a new international multicenter study contradict this conclusion. One hundred patients with vasovagal syncope received pacemakers and then were randomized to dual-chamber pacing or to sensing only.

Among 52 patients who were randomized to pacing, 42% experienced recurrent syncope in the ensuing 6 months, compared with 33% of patients in the sensing-only group -- a nonsignificant difference. Relative risk reduction in the time to recurrent syncope also did not differ significantly between the 2 groups. Complications of pacemaker placement included lead dislodgement or repositioning, vein thrombosis, infection, and cardiac tamponade.

Comment: This study differs from previous smaller studies that showed benefit for pacemaker therapy: In this study, all patients received pacemakers, and patients and physicians were double-blinded to treatment-group assignment. In addition, relatively low rates of bradycardia and asystole were documented at the time of recurrent syncope. Both of these findings could explain why this study showed no significant benefit for pacemaker therapy. The authors recommend that pacing not be used as a first-line therapy for vasovagal syncope. An editorialist points out that medical therapy for this condition also is far from optimal and suggests that breakthroughs will occur only when we better understand the complex pathophysiology of this entity.

— Kirsten E. Fleischmann, MD, MPH

Published in Journal Watch General Medicine May 23, 2003

Citation(s):

Connolly SJ et al. 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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• Medline abstract (Free)

Kapoor WN. Is there an effective treatment for neurally mediated syncope? JAMA 2003 May 7; 289:2272-5.

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• Medline abstract (Free)