Cardiac pacing does not improve orthostatic tolerance in patients with vasovagal syncope.

This study was undertaken to assess the value of dual chamber pacing in the treatment of vasovagal syncope. In a preliminary study, on two patients the time to presyncope during head-up tilt before and after implanting pacemakers was determined. Both patients fainted with similar decreases in blood pressure at almost exactly the same time after tilting. In the main study, nine patients with pacemakers implanted as treatment for syncope were studied, in random order, with pacemakers on and either off or turned to minimum rate. The pacemakers prevented bradycardia but had no effect on the time to syncope in a progressive test of head-up tilt followed by the addition of graded lower body suction. It is concluded that cardiac pacing does not prevent or even delay the onset of postural syncope and infer that bradycardia is an unimportant component of vasovagal attacks.