A number of studies have evaluated the effect of cardiac pacing for prevention of tilt induced vasovagal syncope. The findings are relatively consistent. Pacing does not prevent the onset of vasovagal syncope. This is predictable since hypotension (vasodepressor effect) typically occurs prior to bradycardia. However, dual chamber may prolong the presyncopal period in patients with a prominent cardioinhibitory component. Further, the relation of laboratory observations to spontaneous events is uncertain. In the largest retrospective assessment of pacing efficacy, 89% of patients reported improved symptoms and 62% remained free of symptom recurrence over 50 months.