Dispersion of the QTend, QTpeak and Tpeak‐Tend Interval: Comparison of Reproducibility in Normal Subjects and Patients with Hypertrophic Cardiomyopathy

Background Prolonged QT interval and QT dispersion have been reported to be associated with arrhythmogenesis in patients with cardiac disorders. However, the use of QT dispersion for risk stratification is limited by its low reproducibility. Recently, measurement of the interval between the peak and the end of the T wave (T p ‐T e interval) has been suggested for detection of repolarization abnormalities, but its clinical utility has not been studied in a systematic fashion. Methods This study assessed the intrasubject reproducibility of automatic measurements of QT end , QT peak , and T p ‐T e interval dispersion in 71 normal subjects and 37 patients with hypertrophic Cardiomyopathy (HC). A set of 20 ECGs (10 in supine and 10 in standing position) was evaluated in each subject. Measurements were performed automatically using an advanced commercial computer system. Results HC patients showed significantly higher values of QT tend , QT peak , T p ‐T e intervals, and QT end , QT peak dispersion compared to normal subjects (42 ± 20 vs 20 ± 12 ms and 45 ± 24 vs 33 ± 12 ms, respectively; P < 0.04), but no significant difference was observed in T p ‐T e dispersion between both groups (32 ± 16 vs 29 ± 8 ms; NS). The reproducibility of QT end , QT peak , and T p ‐T e dispersion, expressed as coefficients of variation, was poor in both groups (14%‐28% in normal subjects and 18% to 37% in HC patients). Conclusion Despite higher values of QT end , QT peak T p ‐T e intervals and QT end , QT peak dispersion in HC patients than in normal subjects, T p ‐T e dispersion was similar in both groups. The reproducibility of QT end , QT peak , and T p ‐T e dispersion was low. Automatic measurement of Tp‐Tp dispersion failed to differentiate normal subjects and HC patients.