Key result
Patients with early repolarization syndrome had a significantly smaller 24-hour QT/RR slope compared to healthy controls (0.105 vs 0.161; P<0.001), indicating depressed repolarization dynamics.
Why the study?
Do ventricular repolarization dynamics differ between patients with early repolarization syndrome, uneventful early repolarization pattern, and healthy controls?
Observational (n=145)
Do ventricular repolarization dynamics differ between patients with early repolarization syndrome, uneventful early repolarization pattern, and healthy controls?
Patients with early repolarization syndrome exhibit impaired diurnal and nocturnal adaptation of the QT interval to heart rate, which may provide a substrate for ventricular fibrillation.
Impaired QT adaptation may signal VF risk in early repolarization syndrome; leaves open whether dynamics predict events prospectively.
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.
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Talib et al. (2012) conducted an observational in Early Repolarization Syndrome (n=145). Early Repolarization Syndrome vs. Uneventful ER pattern and healthy controls was evaluated on 24-hour QT/RR slope (p=<0.001). Patients with early repolarization syndrome had a significantly smaller 24-hour QT/RR slope compared to healthy controls (0.105 vs 0.161; P<0.001), indicating depressed repolarization dynamics.
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