Role of pacing in the treatment of vasovagal syncope.

Patients with frequent vasovagal syncope have a markedly poor quality of life and are often resistant to treatment by standard pharmacologic approaches. Although the evidence is not conclusive, clinical vasovagal syncope is probably associated with some degree of bradycardia. Studies of temporary pacing during tilt-table testing have shown that pacing prevents syncope in more than half of patients who develop a vasovagal response. Three open-label studies of permanent pacing showed that pacing was associated with substantial improvement, and the prospective randomized Vasovagal Pacemaker Study reported an 85% relative risk reduction in patients randomized to pacemaker therapy compared with medical therapy. The roles of specific pacemaker modes in vasovagal syncope have not been determined, although early evidence indicates that rate-drop responsiveness is useful. The second Vasovagal Pacemaker Study may clarify the role of rate-drop responsiveness.