Impaired Ventricular Repolarization Dynamics in Patients with Early Repolarization Syndrome

QT Dynamics in Early Repolarization Syndrome Introduction Almost all current investigations on early repolarization syndrome (ERS) have focused on the J-wave characteristics and ST-segment configuration; however, few have reported on ventricular repolarization indexes in ERS. Methods and Results A total of 145 subjects were enrolled: 10 ERS patients, 45 uneventful ER pattern (ERP) subjects, and 90 healthy controls without J waves or ST-segment elevation. Ambulatory ECG-derived parameters (QT, QTc(B), QTc(F), T peak-Tend(Tpe), and QT/RR slope) were measured and statistically compared. Among the groups, there was no significant difference in the average QT and QTc(B); however, ERS patients had the shortest QTc(F) and longest Tpe (QTc(F): 396.2 +/- 19 vs 410.4 +/- 20 vs 419.2 +/- 19 milliseconds, P = 0.036, Tpe: 84.9 +/- 12 vs 70.4 +/- 11 vs 66.9 +/- 15 milliseconds, P < 0.001, for the ERS, ERP, and control groups, respectively). Importantly, the 24-hour QT/RR slope was significantly smaller in the ERS than ERP and control groups (QT/RR: 0.105 +/- 0.01 vs 0.154 +/- 0.02 vs 0.161 +/- 0.03, respectively; P < 0.001). When analyzing the diurnal and nocturnal QT/RR slopes, ERS patients had small diurnal and nocturnal QT/RR slopes while the ERP and control groups had large diurnal and small nocturnal QT/RR slopes (diurnal QT/RR: 0. 077 +/- 0.01 vs 0.132 +/- 0.03 vs 0.143 +/- 0.03, P < 0.001; nocturnal QT/RR: 0.093 +/- 0.02 vs 0.129 +/- 0.03 vs 0.130 +/- 0.04, P = 0.02 in the ERS, ERP, and control groups, respectively). Conclusion ERS patients had a continuously depressed diurnal and nocturnal adaptation of the QT interval to the heart rate. Such abnormal repolarization dynamics might provide a substrate for reentry and be an important element for developing ventricular fibrillation in the ERS cohort.