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

The role of cardiac pacing for treatment of recurrent neurally mediated syn cope (NMS) remains controversial. We hypothesized that dual chamber pacing in NMS patients with a prominent cardioinhibitory component may be benefici al. 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 t able evaluation. Patients were passively tilted to 70 degrees heard-up posi tion for 20 minutes and then returned to the supine position. Isoproterenol was then infused at 1-2 mu g/min to increase heart rate by 25% and tilt wa s repeated. Patients lost consciousness after 16 +/- 6 minutes of tilt; nin e 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 deceleration in response to bradycardia was implanted in all patients. During a mean followup of 18.6 +/- 4.2 mont hs, 11 (92%) of these patients were free of syncope and had negative tilt t able test. One (8%) patient had two episodes of syncope. We conclude that d ual chamber pacing may be beneficial in patients with NMS with a prominent cardioinhibitory component.