Abstract
To facilitate the precision of clinical electrocardiographic studies of J-to-Tpeak (JTp) and Tpeak-to-Tend (Tpe) intervals, the study investigated their differences between healthy females and males, and between subjects of African and Caucasian origin. In 523 healthy subjects (254 females; 236 subjects of African origin), repeated Holter recordings were used to measure QT, JT, JTp, and Tpe intervals preceded by both stable and variable heart rates. Subject-specific curvilinear regression models were used to obtain individual QTc, JTc, JTpc and Tpec intervals. Rate hysteresis, i.e., the speed with which the intervals adapted after heart rate changes, was also investigated. In all sex-race groups, Tpe intervals were not systematically heart rate dependent. Similar to QTc intervals, women had JTc, and JTpc intervals longer than males (difference 20–30 ms, p < 0.001). However, women had Tpec intervals (and rate uncorrected Tpe intervals) shorter by approximately 10 ms compared to males (p < 0.001). Subjects of African origin had significantly shorter QTc intervals than Caucasians (p < 0.001). Gradually diminishing race-difference was found for JTc, JTpc and Tpec intervals. JTc and JTpc were moderately increasing with age but Tpe/Tpec were not. Rate hysteresis of JTp was approximately 10% longer compared to that of JT (p < 0.001). In future clinical studies, Tpe interval should not be systematically corrected for heart rate and similar to the QT interval, the differences in JT, JTp and Tpe intervals should be corrected for sex. The differences in QT and JT, and JTp intervals should also be corrected for race.
Highlights
During the past decade, number of published studies were devoted to the association of cardiovascular and arrhythmic risk with changes of sub-sections of the QT interval measured on standard electrocardiograms (ECG)[1]
Race influence on the normal values of the JTp and Tpe intervals has been little studied. To contribute to this knowledge gap, we have investigated the position of the T peak in ECGs extracted from 12-lead Holter recordings of a relatively large population of healthy volunteers of both sexes involving approximately the same numbers of subjects of African and Caucasian origin
Whilst the main goal of the study was to investigate the sex and race differences in the JT, JTp and Tpe intervals, the accuracy of the data that we report depends on the validity of rate corrections
Summary
Number of published studies were devoted to the association of cardiovascular and arrhythmic risk with changes of sub-sections of the QT interval measured on standard electrocardiograms (ECG)[1]. Further studies are still needed to solve the present conundrum of the electrophysiologic properties and meaning of the ECG intervals involving the T wave peak Among others, it is not known whether future risk prediction studies based on the JTp and Tpe intervals should use different sex-specific limits of normality comparable to the well-known sex-specific QTc interval dichotomies[8]. Race influence on the normal values of the JTp and Tpe intervals has been little studied To contribute to this knowledge gap, we have investigated the position of the T peak in ECGs extracted from 12-lead Holter recordings of a relatively large population of healthy volunteers of both sexes involving approximately the same numbers of subjects of African and Caucasian origin. We include www.nature.com/scientificreports justification of the rate correction technology[9] and show that the accuracy of the correction is sex and race independent
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