Evaluation of a Single Stage Nitroglycerin Tilt Table Test for Diagnosis of Neurally Mediated Syncope

The purpose of this study was to compare clinical outcomes between a single stage head-up tilt table test (HUT) with infusion of 3.44 microg/kg per hour of nitroglycerin and a conventional multistage test with infusion of nitroglycerin from 1.72 microg/kg per hour to 5.16 microg/kg per hour in five successive stages. Thirty-seven patients with recurrent syncope underwent both tests in a prospective, randomized, crossoverfashion. During single stage HUT, a positive response occurred in 24 (64.9%) patients with unexplained syncope, an exaggerated response occurred in 3 (8.1%), a negative response in 7 (18.9%), and drug intolerance in 3 (8.1%). During the multistage HUT, these percentages were 62.2%, 16.2%, 13.5%, and 8.1%, respectively. Twenty healthy control subjects were involved in both tests, One of the control subjects had a positive response to single stage HUT, and two (10%) patients to multistage HUT. The duration of the test in single stage HUT was shorter than that in multistage HUT (8.6 +/- 10.3 vs 38.6 +/- 32.1 minutes, P < 0.01). The results showed that the single stage HUT was a fairly sensitive, specific, and a time-efficient test for provoking neurally mediated syncope.