Repolarization measures and their relation to sex hormones in postmenopausal women with cardiovascular disease receiving hormone replacement therapy

Abstract

Women are more susceptible to the development of Torsades de Pointes ventricular tachycardia and have a longer heart rate-corrected QT interval than men. A causal role for estrogen has been implicated. The purpose of this study was to investigate if hormone replacement therapy (HRT) resulted in any changes in noninvasive depolarization and repolarization measurements, and to study their relation to circulating concentrations of sex hormones. Sixty postmenopausal women with cardiovascular disease (mean age 59 ± 7 years; range 44 to 75) were randomized to receive oral conjugated estrogens, transdermal estradiol-17-β (both with addition of progestins), or placebo. QRS, QT, and JT intervals and their dispersion on 12-lead electrocardiograms were analyzed at baseline, and after 6 and 12 treatment cycles of HRT. Blood samples for analyses of serum concentration of estrogens and androgens were obtained on the same occasions. Neither mean RR, QT, QTc, JT, and JTc intervals, nor QT and JT dispersion changed during treatment. There was a significant inverse relation between the mean JTc interval and the serum concentration of estradiol-17-β, independent of age, testosterone levels, and abdominal obesity. There was also a significant inverse relation between the change in androstenedione levels and the change in QT interval (Spearman −0.35, p = 0.028) or JT interval (Spearman −0.41, p = 0.009) at 6 treatment cycles compared with baseline. In conclusion, treatment with oral conjugated estrogens or transdermal estradiol-17-β combined with progestins did not alter depolarization or repolarization measurements. However, the inverse relation between repolarization and androgens fits with an effect of androgens on repolarization in postmenopausal women.