Abstract P008: Short-Term Repeatability of Electrocardiographic Tpeak-Tend Interval
Background: The Tpeak-Tend interval (Tp-Te) from the resting standard, twelve-lead electrocardiogram (ECG) is a measure of myocardial repolarization that is associated with ventricular arrhythmia and sudden cardiac death. The Tp-Te interval has gained attention as an alternative measure for the traditional QT interval yet its repeatability has not been established.
Objectives: To examine and compare the short-term repeatability and the minimal detectable change (MDC) of Tp-Te and the QT interval.
Methods: Technicians trained and certified on the Atherosclerosis Risk in Communities (ARIC) ECG protocol obtained 4 ECGs (2 per visit, one week apart) on 63 volunteer participants. The ECGs were centrally processed using the Marquette GE program to calculate Tp-Te as the duration (ms) between the peak (Tp) and end (Te) of the T wave. After excluding 1 participant due to invalid data, we used random-effects, mixed models to estimate the between-participant, between-visit, and within-visit sources of variation in Tp-Te, and we calculated the intra-class correlation coefficient (ICC); and the MDC with 95% confidence.
Results: Between-participant variation accounted for 87% (425 out of 487) of the total variation in the Tp-Te interval (an estimate unchanged after log transformation). The ICC (95% confidence interval [CI]) of the Tp-Te interval was 0.87 (0.82, 0.92) and 0.85 (0.80, 0.91) before and after log transformation. For comparison, the ICC (95% CI) for the QT interval was 0.89 (0.84, 0.93). The MDC between two measures was 22 ms and 0.23 for Tp-Te and log Tp-Te, whereas the MDC for QT duration was 32 ms. All three MDC measures are approximately equal to the standard deviations.
Conclusion: The Tp-Te interval has excellent short-term repeatability as the between-person variability accounts for most of the total variability of the measurement. As an alternative measure of myocardial repolarization, the MDC estimate of the Tp-Te interval compares favorably to that of the QT interval. The high repeatability and low MDC between measurements support the use of the Tp-Te interval in observational and clinical studies evaluating risk of ventricular arrhythmia and sudden cardiac death.
- © 2013 by American Heart Association, Inc.