Dual chamber pacing for neurally mediated syncope with a prominent cardioinhibitory component.

The role of cardiac pacing for treatment of recurrent neurally mediated syncope (NMS) remains controversial. We hypothesized that dual chamber pacing in NMS patients with a prominent cardioinhibitory component may be beneficial. Twelve patients (mean age = 37.8 ± 17 years, range 15–78 years, 7 men and 5 women) with a mean of 4 ± 2.2 episodes of syncope underwent tilt table evaluation. Patients were passively tilted to 70° head-up position for 20 minutes and then returned to the supine position. Isoproterenol was then infused at 1–2 μg/min to increase heart rate by ≥ 25% and tilt was repeated. Patients lost consciousness after 16 ± 6 minutes of tilt; nine patients had syncope in the baseline state and three during isoproterenol infusion. All patients had at least 5 seconds of asystole with a mean of 9.5 ± 4 seconds (range 5–20 s). A dual chamber permanent pacemaker with a special feature allowing heart rate acceleration in response to bradycardia was implanted in all patients. During a mean follow-up of 18.6 ± 4.2 months, 11 (92%) of these patients were free of syncope and had negative tilt table test. One (8%) patient had two episodes of syncope. We conclude that dual chamber pacing may be beneficial in patients with NMS with a prominent cardioinhibitory component.