Vasovagal syncope with asystole: the role of cardiac pacing

Whereas cardiac pacing has a very limited role overall in patients with vasovagal syncope (VVS), there are three reasons which support pacing efficacy in tilt-induced asystolic VVS. These are: (1) contrary to mixed and vasodepressor forms, an asystolic tilt response is specific, i.e., diagnostic, of VVS and is unlikely to occur in control patients without history of syncope and in patients with cardiac syncope; (2) contrary to mixed and vasodepressor forms, an asystolic tilt response predicts a similar asystolic event during prolonged ECG monitoring with a positive predictive value of 86%; (3) the available evidence from trials supports the efficacy of dual-chamber pacing with a low recurrence rate of syncope after pacing ranging from 6% up to 23% during 3 years of follow-up. The latter results should be confirmed by an ongoing double-blind randomized controlled trial before cardiac pacing becomes an established indication. It is commonly believed that the most frequent cause of recurrence of syncope in patients treated with a pacemaker is an associated hypotensive reflex. In these cases additional measures should be used to counteract hypotension. Recognizing prodromal symptoms, avoiding triggers, and performing counterpressure maneuvers are the well-known first steps. There are two additional useful measures when these fail: stopping/reducing hypotensive drugs and (in selected cases) adding fludrocortisone.