Ventricular repolarization abnormalities increase the risk of ventricular arrhythmias, and prolongation and shortening of the electrocardiographic QT interval increase the risk of SCD. 4,5 However, the association between QT duration and SCD in the general population has been relatively weak. Recently, an association between prolongation of the T-wave peak to T-wave end interval (TPE) and SCD was found in a general population sample.6 Furthermore, computerized measures of the 3-dimensional T-wave loop, the T-wave morphology parameters, have contained prognostic value for cardiovascular morbidity and mortality in several population studies, 7−12 but their relation specifically to SCD is less clear. The aim of the present study was to test the hypothesis that TPE and T-wave morphology parameters predict SCD in the general population.© 2013 American Heart Association, Inc. Original ArticleBackground-Previous population studies have found an association between electrocardiographic T-wave morphology parameters and cardiovascular mortality, but their relationship to sudden cardiac death (SCD) is not clear. To our knowledge, there are no follow-up studies assessing the association between electrocardiographic T-wave peak to T-wave end interval (TPE) and SCD. We assessed the predictive value of electrocardiographic T-wave morphology parameters and TPE for SCD in an adult general population sample. Methods and Results-A total of 4 T-wave morphology parameters (principal component analysis ratio, T-wave morphology dispersion, total cosine R-to-T, T-wave residuum) as well as TPE were measured from digital standard 12-lead ECGs in 5618 adults (46% men; mean age 50.9±12.5 years) participating in the Finnish population-based Health 2000 Study. After a mean follow-up time of 7.7±1.4 years, 72 SCDs had occurred. In univariable analyses, all T-wave morphology parameters were associated with an increased SCD risk. In multivariable Cox models, T-wave morphology dispersion and total cosine R-to-T remained as predictors of SCD, with T-wave morphology dispersion showing the highest SCD risk (hazard ratio of 1.4 [95% confidence interval 1.1−1.7, P=0.001] per 1 SD increase in the log e T-wave morphology dispersion). In contrast, TPE was not associated with SCD in univariable or multivariable analyses. Conclusions-Electrocardiographic T-wave morphology parameters describing the 3-dimensional shape of the T-wave stratify SCD risk in the general population, but we did not find an association between TPE and SCD.

Background-Transmural dispersion of repolarization (TDR) may be related to the genesis of torsade de pointes (TdP) in patients with the long-QT (LQT) syndrome. Experimentally, LQT2 models show increased TDR compared with LQT1, and ␤-adrenergic stimulation increases TDR in both models. Clinically, LQT1 patients experience symptoms at elevated heart rates, but LQT2 patients do so at lower rates. The interval from T-wave peak to T-wave end (TPE interval) is the clinical counterpart of TDR. We explored the relationship of TPE interval to heart rate and to the presence of symptoms in patients with LQT1 and LQT2. Methods and Results-We reviewed Holter recordings from 90 genotyped subjects, 31 with LQT1, 28 with LQT2, and 31 from unaffected family members, to record TPE intervals by use of an automated computerized program. The median TPE interval was greater in LQT2 (112Ϯ5 ms) than LQT1 (91Ϯ2 ms) or unaffected (86Ϯ3 ms) patients (PϽ0.001 for all group comparisons), and the maximal TPE values differed as well. LQT1 patients showed abrupt increases in TPE values at RR intervals from 600 to 900 ms, but LQT2 patients did so at RR intervals from 600 to 1400 ms (longest RR studied). Asymptomatic and symptomatic patients showed similar TDRs. Conclusions-TDR is greater in LQT2 than in LQT1 patients. LQT1 patients showed a capacity to increase TDR at elevated heart rates, but LQT2 patients did so at a much wider rate range. The magnitude of TDR is not related to a history of TdP. Key Words: arrhythmia Ⅲ electrocardiography Ⅲ long-QT syndrome Ⅲ torsade de pointes T orsade de pointes is the arrhythmia producing syncope and risk of sudden death in patients with the congenital long-QT syndrome (LQTS). 1 Torsade de pointes tends to appear during exercise (especially swimming) or psychological stress in LQT1, during stress or startle (particularly auditory stimuli) in LQT2, and during rest in LQT3. 2 In experimental LQTS models, transmural dispersion of repolarization (TDR) has been linked to the genesis of torsade de pointes, 3 and LQT2 shows increased TDR, determined as the action potential duration difference between midmyocardial and epicardial cells, compared with LQT1 and normal hearts. 4 Conversely, ␤-adrenergic stimulation increases TDR in both LQTS models, transiently in LQT2 and persistently in LQT1. 4 In addition, the interval from QRS onset to the T-wave termination and T-wave apex correspond to action potential durations of midmyocardial and epicardial cells, respectively. 5 We hypothesized that the T-wave peak to T-wave end (TPE) interval would prolong preferentially with abrupt elevation of heart rates in LQT1 patients, whereas LQT2 patients would show prolonged TPE intervals at a wider range of heart rates. Although earlier studies have shown a weak correlation between the length of the QT interval and symptoms, 6,7 we hypothesized that the history of cardiac symptoms may be related to TPE interval rather than the length of the QT interval. Methods Study SubjectsWe reviewed Holter recordings in 90 individuals either ...