Cardioinhibition during tilt testing identifies patients who may benefit from pacing

This study examined whether the various hemodynamic collapse patterns observed during tilt testing in patients with suspected neurocardiogenic syncope are relevant when planning therapy, particularly whether a predominantly cardioinhibitory response predicts a beneficial response from pacing.

The effects of temporary atrioventricular (A-V) sequential pacing were studied during tilt testing in 34 patients 48.2 +/- 18.5 years of age. The patient population was divided into a cardioinhibitory group (VASIS classes 2A and 2B) or mixed group (VASIS classes 1 and 3) according to their response to baseline tilt testing. The test was then repeated during A-V pacing with rate hysteresis. A positive response to A-V pacing was defined as a > or = 30-second increase between onset of symptoms and syncope, or mitigation of symptoms compared with the baseline tilt test.

The study protocol was not successfully completed in three patients. Among the remaining 31 patients, a baseline cardioinhibitory response was observed in 17, and a mixed response in 14 patients. A-V sequential pacing was successful in 13 of 17 patients with a cardioinhibitory response versus 5 of 14 patients with a mixed response (P = 0.024).

The presence of a predominantly cardioinhibitory collapse pattern (VASIS 2A and 2B) during baseline tilt testing doubled the likelihood of successful temporary A-V sequential pacing, and may identify patients with neurocardiogenic syncope most likely to benefit from permanent dual chamber pacing.