Short-duration head-up tilt test potentiated with sublingual nitroglycerin in suspected vasovagal syncope: the fast Italian protocol

Background The traditional nitroglycerin (NTG) head-up tilt test (HUTT) is time-consuming and the test duration is a barrier to widespread utilization in clinical practice. It was hypothesized that a short-duration protocol is not inferior to the traditional protocol regarding the positivity rate and has a similar distribution of hemodynamic response. Methods and results Patients undergoing HUTT were randomized 1:1 to a 10 min passive phase plus a 10 min 0.3 mg NTG if the passive phase was negative (Fast) or to a 20 min passive phase plus a 15 min 0.3 mg NTG if the passive phase was negative (Traditional). A sample size of 277 patients for each group achieved 80% power to detect an expected difference of 0% with a non-inferiority margin of -10% using a one-sided t-test and assuming a significant level alpha of 0.025. A total of 554 consecutive patients (mean age 46.6 +/- 19.3 years, 47.6% males) undergoing HUTT for suspected vasovagal syncope were randomly assigned to the Fast (n = 277) or Traditional (n = 277) protocol. A positive response was defined as the induction of syncope in presence of hypotension/bradycardia, and was observed in 167 (60.3%) patients with Fast and in 162 (58.5%) patients with the Traditional protocol. There was a trend of lesser vasodepressor response (14.8% Fast vs. 20.6% Traditional) which was significant during the passive phase (P = 0.01). Conclusion The diagnostic value of the Fast HUTT protocol is similar to that of the Traditional protocol and therefore the Fast protocol can be used instead of the Traditional protocol.