Prediction evaluation of the Tp-Te interval in patients with vasovagal syncope.

Purpose: Vasovagal syncope (VVS) involves autonomic dysregulation affecting cardiac electrical activity. The Tp-Te interval, reflecting transmural repolarization dispersion, may help predict positive head-up tilt test (HUTT) responses in patients with suspected VVS.

Methods: A total of 179 patients with suspected VVS were included in the study. A HUTT was performed in enrolled patients, which were divided into HUTT-negative and HUTT-positive groups, and the HUTT-positive group was further classified into three subgroups of "vasodepressor," "cardioinhibitory," and "mixed-type" responses to HUTT. QT interval, corrected QT (QTc) interval, and Tp-Te interval were measured by the baseline 12-lead surface electrocardiograph recorded before HUTT.

Results: The QT interval, QTc interval, and Tp-Te interval in the HUTT-positive group were higher than those in the HUTT-negative group (P < 0.001). Tp-Te was higher in the cardioinhibitory and mixed-type subgroups than in the vasodepressor subgroup (P < 0.05). Receiver operating characteristic curve analysis showed that Tp-Te higher than 88 ms was a significant predictor of positive HUTT results (71.70% sensitivity and 75.90% specificity), with a predictive value significantly higher than QT and QTc (P < 0.05), and Tp-Te higher than 95 ms predicted cardioinhibitory and mixed-type response to HUTT (75% sensitivity, and 57.10% specificity).

Conclusion: Baseline myocardial TDR is associated with VVS and susceptibility to VVS. The baseline Tp-Te interval might be used as a novel noninvasive index for differentiating cardioinhibitory, mixed-type, and vasodepressor responses to HUTT and for predicting the occurrence of cardioinhibitory responses in VVS patients.