Cardioinhibition during tilt testing identifies patients who may benefit from pacing

This study examined whether the various hemodynamic collapse patterns obser ved during tilt testing in patients with suspected neurocardiogenic syncope are relevant when planning therapy, particularly whether a predominantly c ardioinhibitory response predicts a beneficial response from pacing. Method s: The effects of temporary atrioventricular (A-V) sequential pacing were s tudied during tilt testing in 34 patients 48.2 +/- 18.5 years of age. The p atient population was divided into a cardioinhibitory group (VASlS classes 2A and 2B) or mixed group (VASIS classes 1 and 3) according to their respon se to baseline tilt testing. The test was then repeated during A-Vpacing wi th rate hysteresis. A positive response to A-V pacing was defined as a grea ter than or equal to 30-second increase between onset of symptoms and synco pe, or mitigation of symptoms compared with the baseline tilt test. Results : The study protocol was not successfully completed in three patients. Amon g the remaining 31 patients, a baseline cardioinhibitory response was obser ved in 17, and a mixed response in 14 patients. A-V sequential pacing was s uccessful in 13 of 17 patients with a cardioinhibitory response versus 5 of 14 patients with a mixed response (P = 0.024). Conclusion: The presence of a predominantly cardioinhibitory collapse pattern (VASIS 2A and 2B) during baseline tilt testing doubled the likelihood of successful temporary A-V s equential pacing, and may identify patients with neurocardiogenic syncope m ost likely to benefit from permanent dual chamber pacing.