Dispersion of the QT end , QT peak and T peak -T end Interval: Comparison of Reproducibility in Normal Subjects and Patients with Hypertrophic Cardiomyopathy (original) (raw)

1998, Annals of Noninvasive Electrocardiology

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,-T, 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 QTend, QTpeak, and T,-T, 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 QTend, QTpeak, Tp-Te intervals, and QTend, QTpeak 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,-T, dispersion between both groups (32 ? 16 vs 29 ? 8 ms; NS). The reproducibility of QTend, QTpeak, and T,-T, dispersion, expressed as coefficients of variation, was poor in both groups (1 4%-28% in normal subjects and 18% to 37% in HC patients). Conclusion: Despite higher values of QTend, QTpeak, T,-T, intervals and QTend, QTpeak dispersion in HC patients than in normal subjects, T,-T, dispersion was similar in both groups. The reproducibil-Recently, measurement of the interval between The study was supported in part by the European Society of Cardiology,