Abstract Body (Do not enter title and authors here): Background:
Vasovagal syncope (VVS) is a type of reflex syncope in which transient loss of consciousness is caused by reflex vasodepression and/or cardioinhibition leading to cerebral hypoperfusion. VVS is the most common type of syncope, accounting for more than one third of the types of syncope. A head-up tilt table test (HUTT) can be helpful in confirming this diagnosis. However, the optimal duration of a HUTT in this evaluation is unclear. While many centers use a 10-minute tilt duration, a 45-minute tilt duration may increase diagnostic yield.

Aims:
To assess the time while upright during a HUTT until a vasovagal response occurs.

Methods:
We conducted a retrospective analysis of patients who underwent a 45-minute passive HUTT in the evaluation of clinical symptoms who had a vasovagal response during the test (n = 386). . To assess the diagnostic yield of longer-duration tilt testing (45-minutes), we simulated a shorter duration HUTTs (10-minutes). We then performed a McNemar’s exact test to compare the number of patients who would have been diagnosed by a shorter duration HUTT versus full duration HUTT. Unpaired t-tests were performed to compare the mean time to positivity between subgroups.

Results:
351 out of 386 patients had a positive VVS diagnosis beyond the 12-minute mark of the full-duration HUTT. The average time to positivity was 27.9 ± 11.9 min. Among patients aged >40 years, the mean time to positivity was significantly longer when compared to those ≤40 years (29.8 ± 12.5 min vs. 24.4 ± 11.7 min, p < 0.001). No significant difference was noted between sexes (males: 28.1 ± 12.3 min vs. 27.2 ± 12.4 min, p = 0.533).

Conclusions:
This analysis shows that a 10-minute HUTT excludes many patients with VVS, especially in older patients. These findings support the use of longer-duration HUTT for diagnosing VVS.