Correlation of head-up tilt table test time interval with future risk of recurrent syncope.

Background: Head-up tilt table test (HUTT) is widely used for the investigation of syncope and presyncope. Time required for positive response has a probable relationship to the sensitivity of neural reflex mechanism underlying syncope.

Methods: We evaluated patients with history of syncope. Group A included patients with recurrent syncope defined as two or more episodes of syncope and group B included those with one episode of syncope. Time required for the test to become positive in both the groups was analyzed. Patients with positive HUTT were followed for 1 year.

Results: Of 80 patients, 68 eligible study patients were divided into group A (32.35%) and group B (67.65%). HUTT was positive in 41 patients (positivity rate  =  60.29%). Positivity rate was 100% in group A and 41.3% in group B. Median time interval for positive response in groups A and B were 12.5 and 30.0 minutes, respectively. An inverse association was found between recurrent syncope and time interval for positive response (R  =  - 0.282, P  =  0.002). Time interval of less than 19.5 minutes for positive response had 94.5% sensitivity and 97.89% specificity for recurrent syncope. On follow-up, positive association was found between time interval for positive response less than 19.5 minutes and future recurrence of syncope (odds ratio  =  22.75, 95% confidence interval  =  4.37-118.34, P  =  0.000).

Conclusion: HUTT time interval of less than 19.5 minutes for positive response predicted future recurrence of syncope. Hence, it may serve as an important predictor of future recurrence of syncope.