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 degrees head-up position for 20 minutes and then returned to the supine position. Isoproterenol was then infused at 1-2 microg/min to increase heart rate by > or = 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.