Permanent pacing for cardioinhibitory malignant vasovagal syndrome.

OBJECTIVE To evaluate the effect of permanent pacing in cardioinhibitory malignant vasovagal syndrome. PATIENTS AND METHODS 37 patients with permanent pacemakers for cardioinhibitory malignant vasovagal syndrome. All presented with syncope (median six episodes, median frequency two episodes a year) and after conventional investigation and invasive electrophysiological assessment they remained undiagnosed, and without a generally accepted indication for pacemaker implantation. In all vasovagal syncope with cardioinhibition (heart rate at syncope < 60 beats/min) developed during tilt tests performed according to the Westminster protocol (head up tilt at 60 degrees with a footplate support for 45 minutes or until syncope intervenes). Dual chamber pacemakers were implanted in 35 (95%) and VVI pacemakers in the remaining two (5%). RESULTS Over a mean (SD) follow up since implantation of 50.2 (23.9) months symptomatic improvement occurred in 89%: 62% remained free of syncope and 27% were completely symptom free. The collective syncopal burden of these 37 patients was reduced from 136 to 11 episodes each year. During follow up three patients died from unrelated causes. Patients who become asystolic during the tilt test (sinus pause of at least four seconds) experienced no greater benefit from pacing than those with less extreme cardioinhibition. Patients who remained free of syncope since implantation were younger than those who continued to experience syncope. Patients who remained completely symptom free after implantation were younger, more likely to be male, and had had fewer syncopal episodes before implantation than those who continued to experience syncope or presyncope. No other demographic, clinical, investigative, or pacing variable suggested a more favourable outcome after implant. CONCLUSIONS This retrospective and uncontrolled experience suggests a possible role for permanent pacing in selected patients with cardioinhibitory malignant vasovagal syndrome. Improved acquisition of tilt test data may enable better selection of patients who are suitable for permanent pacing. A randomised prospective study to compare permanent pacing with no treatment or with medical treatment in cardioinhibitory malignant vasovagal syndrome is indicated.