Gender and the relationship between ventricular repolarization and cardiac cycle length during 24-h Holter recordings

Stramba-Badiale, Marco; Locati, Emanuela H.; Martinelli, Alessandra Rezende; Courville, J.; Schwartz, Peter J.

doi:10.1093/oxfordjournals.eurheartj.a015357

Cited by 180 publications

(99 citation statements)

References 27 publications

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“…We therefore cannot compare our principal results with any previous studies. The sex differences in the mean QTc interval as well as in the linear and log-linear slopes correspond well with previous publications (18,35). Contrary to a previous report (27), we found statistically significant sex differences in hysteresis time constants (as well as in previously reported hysteresis coefficients; data not shown).…”

Section: Discussionsupporting

confidence: 90%

QT/RR curvatures in healthy subjects: sex differences and covariates

Malik

Hnatkova²,

Kowalski

et al. 2013

American Journal of Physiology-Heart and Circulatory Physiology

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Data of a large clinical study were used to investigate how much are the QT/RR patterns in healthy subjects curved and whether these curvatures differ between women and men. Daytime drug-free 12-lead Holter recordings were repeated 4 times in each of 176 female healthy subjects and 176 male healthy subjects aged 32.7 Ϯ 9.1 yr. In each of the subjects, up to 1,440 carefully verified QT interval measurements were obtained with QT/RR hysteresis-corrected RR intervals. Individual subject data were used to fit the following regression equation: QT ϭ ϩ (␦/␥)(1 Ϫ RR ␥ ) ϩ ε, where QT and RR are QT and RR measurements (in s), is regression intercept, ␦ is the QT/RR slope, ␥ is the QT/RR curvature and provides the lowest regression residual, and ε represents normally distributed zero-centered errors. The bootstrap technique showed the intrasubject reproducibility of QT/RR slopes and curvatures. In women and men, QT/RR curvatures were 0.544 Ϯ 0.661 and 0.797 Ϯ 0.706, respectively (P ϭ 0.0006). The corresponding QT/RR slopes were 0.158 Ϯ 0.030 and 0.139 Ϯ 0.023, respectively (P Ͻ 0.0001). QT/RR curvatures were related to QT/RR slopes but not to individually corrected mean QTc intervals or individual QT/RR hysteresis profiles. The individual heart rate correction formula derived from the curvilinear regression provided a significantly lower intrasubject variability of QTc interval than individual optimisation of linear or log-linear QT/RR heart rate corrections. The QT/RR curvature can be reliable measured and expressed numerically. The corresponding heart rate correction formula provides more compact data than the previously proposed approaches. There are substantial sex differences in QT/RR patterns. Women have a QT/RR pattern that is not only steeper than men but also more curved.QT/RR curvature profile; intrasubject stability; intersubject differences; QT heart rate correction THE DEPENDENCY of the duration of ventricular repolarization on the underlying heart rate is well known. It is also known that it is related to a similar dependency of action potential durations (7) that shows regional differences within the ventricular myocardium (23). Similarly, delayed adaptation of action potential durations after abrupt changes in stimulation rates are well known (8). The intracellular mechanism underlying the repolarization dependency and thus the pattern of the QT/RR relationship are not completely understood and have been subject of both animal and modeling experiments of ionic currents (11,19,22). Why the QT/RR relationship and adaptation exhibits substantial intersubject differences with intrasubject stability (3, 27) is not known. Further studies of the phenomenon require appropriate tools for the description of the relationship.A number of studies (5, 6, 10, 16) assessed the slope of the QT/RR relationship in long-term Holter recordings and investigated its meaning as a clinical characteristic. The majority of these studies investigated the relationship by means of linear regression between simultaneously measured QT a...

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Section: Discussionsupporting

confidence: 90%

QT/RR curvatures in healthy subjects: sex differences and covariates

Malik

Hnatkova²,

Kowalski

et al. 2013

American Journal of Physiology-Heart and Circulatory Physiology

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“…QT maximum and QT minimum did not differ among the three groups. QT dispersion was not significantly associated with age, gender, or heart rate, which is discordant with some other studies.19, 33+ 34 QT maximum and QT minimum were significantly associated with gender and heart rate, as previously reported.33, 34…”

Section: Qt Dispersion In Systemic Hypertensionsupporting

confidence: 78%

Changes of the t‐wave amplitude and angle: An early marker of altered ventricular repolarization in hypertension

Dilaveris

Gialafos

Poloniecki

et al. 2000

Clinical Cardiology

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summaryBackground: The heterogeneity of ventricular repolarization is an important promhythmic factor. QT dispersion has been proposed to reflect the inhomogeneity of ventricular repolarization, but a poor reproducibility limits its clinical applicability. Reliable noninvasive methods to quantlfy abnormalities in ventricular repolarization are still lacking. The T-loop morphology analysis is a novel method aimed at quantifying ventricular repolarization.Hypothesis: To test the ability of the T-loop morphology analysis to discriminate between hypertensive patients and healthy subjects, 105 hypertensive patients (mean age 63.6 +-12.3 years) and 110 healthy controls (mean age 49.7 f 14.3 years) were evaluated. Methods:The maximum QT interval (QT maximum), the minimum QT interval (QT minimum), and their difference (QT dispersion) were calculated from a digitally recorded 12-lead electrocardiogram (ECG) in both study groups. X, Y, and Z leads were reconstructed from the 12-lead ECG, and the amplitude of the maximum T vector (T amplitude) and the angle between the maximum T vector and X axis (Tangle) were calculated from the projection of the T loop in the frontal plane.

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“…Because women tend to have a higher HR [36] and the difference in gender distribution between groups was substantial (although not significant), we entered gender as covariate for the test of HR. The assumptions of the repeated measures ANCOVA were not violated for HR, however according to the Q-Q plots and KolmogorovSmirnov tests, error terms did not follow normal distribution for Well-being and Calmness.…”

Section: Hypothesis Testingmentioning

confidence: 99%