Evaluation of the Tp-Te interval, Tp-Te/QTc ratio, and QT dispersion in patients with Turner syndrome

Effect of Empagliflozin Treatment on Ventricular Repolarization Parameters

Background

An example of a sodium-glucose cotransporter-2 (SGLT-2) inhibitor is Empagliflozin. It is a new medicine for treating type 2 diabetes mellitus (T2DM), but there is increasing interest in how empagliflozin affects the heart. This study aims to examine the impact of empagliflozin treatment on ventricular repolarization parameters in T2DM patients.

Methods

T2DM patients were included in a prospective study. Measurements of ventricular repolarization parameters, including QT interval, corrected QT interval (QTc), QT dispersion (QTd), Tpeak-to-Tend interval (Tp-e), and Tpeak-to-Tend interval corrected for QTc (Tp-e/QTc), were obtained before initiating empagliflozin treatment and six months following treatment initiation. Statistical analysis was performed to assess changes in these parameters.

Results

In this study, 95 patients were diagnosed with T2DM out of 177 patients. Among T2DM patients, 40 were male (42%) compared to 48% males in controls (p = 0.152). The average age of the T2DM patients was 60.2 ± 9.0 years, compared to 58.2 ± 9.2 years in the control group (p = 0.374). When comparing pre- and post-treatment measurements of parameters representing ventricular repolarization (QT 408.5 ± 22.9/378.8 ± 14.1, p < 0.001; QTc 427.0 ± 20.5/404.7 ± 13.8, p < 0.001; QTd 52.1 ± 1.2/47.8 ± 1.7, p < 0.001; Tp-e 82.3 ± 8.7/67.1 ± 5.1, p < 0.001; Tp-e/QTc 0.19 ± 0.01/0.17 ± 0.01, p < 0.001 (respectively)), statistically significant improvements were observed. A statistically significant dose-dependent decline in the magnitude of change in the QTc parameter (19.4/29.6, p = 0.038) was also observed.

Conclusions

According to these results, empagliflozin may decrease the risk of potential ventricular arrhythmias.

Cardiac abnormalities in girls with Turner syndrome: ECG abnormalities, myocardial strain imaging, and karyotype-phenotype associations

Turner syndrome (TS) is a chromosomal condition which is associated with an increased prevalence of cardiac morbidity and mortality. In this cross‐sectional study, Minnesota‐based electrocardiographic (ECG) abnormalities, aortic dimensions, routine‐ and myocardial strain echocardiographic parameters, and karyotype‐cardiac phenotype associations were assessed in girls with TS. In total, 101 girls with TS (0–18 years) were included. The prevalence of major ECG abnormalities was 2% (T‐wave abnormalities) and 39% had minor ECG abnormalities. Dilatation of the ascending aorta (z‐score > 2) was present in 16%, but the prevalence was much lower when using TS‐specific z‐scores. No left ventricular hypertrophy was detected and the age‐matched global longitudinal strain was reduced in only 6% of the patients. Cardiac abnormalities seemed more common in patients with a non‐mosaic 45,X karyotype compared with other karyotypes, although no statistically significant association was found. Lowering the frequency of echocardiography and ECG screening might be considered in girls with TS without cardiovascular malformations and/or risk factors for aortic dissection. Nevertheless, a large prospective study is needed to confirm our results. The appropriate z‐score for the assessment of aortic dilatation remains an important knowledge gap. The karyotype was not significantly associated with the presence of cardiac abnormalities, therefore cardiac screening should not depend on karyotype alone.

Sexual Dimorphisms, Anti-Hormonal Therapy and Cardiac Arrhythmias

Significant variations from the normal QT interval range of 350 to 450 milliseconds (ms) in men and 360 to 460 ms in women increase the risk for ventricular arrhythmias. This difference in the QT interval between men and women has led to the understanding of the influence of sex hormones on the role of gender-specific channelopathies and development of ventricular arrhythmias. The QT interval, which represents the duration of ventricular repolarization of the heart, can be affected by androgen levels, resulting in a sex-specific predilection for acquired and inherited channelopathies such as acquired long QT syndrome in women and Brugada syndrome and early repolarization syndrome in men. Manipulation of the homeostasis of these sex hormones as either hormonal therapy for certain cancers, recreational therapy or family planning and in transgender treatment has also been shown to affect QT interval duration and increase the risk for ventricular arrhythmias. In this review, we highlight the effects of endogenous and exogenous sex hormones in the physiological and pathological states on QTc variation and predisposition to gender-specific pro-arrhythmias.

No QTc Prolongation in Girls and Women with Turner Syndrome

CONTEXT

Turner syndrome (TS) is a genetic condition that is reported to be associated with a prolonged rate-corrected QT (QTc) interval.

OBJECTIVES

To evaluate the prevalence of QTc prolongation in patients with TS, to compare their QTc intervals with healthy controls, and to investigate whether QTc prolongation is associated with a monosomy 45,X karyotype.

METHOD

Girls (n = 101) and women (n = 251) with TS visiting our center from 2004-2018 were included in this cross-sectional study. QT intervals of 12-leaded electrocardiograms were measured manually, using Bazett's and Hodges formulas to correct for heart rate. A QTc interval of >450 ms for girls and >460 ms for women was considered prolonged. Corrected QT (QTc) intervals of patients with TS were compared to the QTc intervals of healthy girls and women from the same age groups derived from the literature.

RESULTS

In total, 5% of the population with TS had a prolonged QTc interval using Bazett's formula and 0% using Hodges formula. Mean QTc intervals of these patients were not prolonged compared with the QTc interval of healthy individuals from the literature. Girls showed shorter mean QTc intervals compared with women. We found no association between monosomy 45,X and prolongation of the QTc interval.

CONCLUSIONS

This study shows that the QTc interval in girls and women with TS is not prolonged compared with the general population derived from the literature, using both Bazett's and Hodges formulas. Furthermore, girls show shorter QTc intervals compared with women, and a monosomy 45,X karyotype is not associated with QTc prolongation.