Sex-Specific heart rate acceleration as predictors of positive head-up tilt test outcomes in syncope patients.

BACKGROUND: Head-up tilt test (HUTT) is widely used to evaluate patients with unexplained syncope, but data on clinical predictors of HUTT results are limited. This study aimed to evaluate heart rate (HR) acceleration and blood pressure (BP) changes associated with the HUTT results in syncope patients and the differences according to sex. METHODS: A cross-sectional study was performed with patients who presented with unexplained syncope and were subjected to HUTT (70-degree angle) from January 2011 to April 2015. BP changes and Receiver Operating Characteristic (ROC) curves for the maximum interval in HR acceleration from the first to the tenth minute (delta-HR 10) after tilting were analyzed. The significance level was set at 5%. RESULTS: Of 149 patients (mean age: 28.5 ± 29 years), 40 (26.85%) had a positive HUTT. The delta-HR 10 acceleration was higher in the positive group (14.0 ± 9.25 bpm vs. 9.0 ± 11 bpm, p = 0.002). When considering sex, a cut-off point of 12 bpm was found, with an area under the curve of 0.805 for females, showing a sensitivity of 80% and a negative predictive value of 91.2%, and an area under the curve of 0.580 for males, with a sensitivity of 52% and a negative predictive value of 73.9%. CONCLUSIONS: The HR acceleration of 12 bpm up to the tenth minute after tilting was an independent predictor of a positive HUTT in female syncope patients, demonstrating good sensitivity, accuracy, and negative predictive value. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT06496074.