In a second study, published in the HeartRhythm Journal, Koren and his colleagues furthered their understanding of arrhythmias by studying the impact of sex hormones, and confirming for the first time a direct link between the hormones and SCD.
Koren explains, "Quite simply, we demonstrate that estrogen promotes major cardiac events such as polymorphic ventricular tachycardia (pVT) and SCD while progesterone prevents them when LQT2 is a factor. Estrogen has a pro-arrhythmic effect."
Sex differences in long-QT-related arrhythmias with a higher risk of pVT and SCD have been well-documented in the clinical setting, and the risk is higher in women than in men, particularly during the postpartum period. In this study, Koren says, "We show for the first time a direct link between sex hormones and the incidence of arrhythmias and sudden cardiac death. Through our research in our animal models, we have demonstrated that progesterone significantly reduces triggers for polymorphic ventricular tachycardia. At the same time, we were able to show that progesterone is protective and prevents SCD when LQT2 is present."
Koren explains that this finding suggests that high progesterone levels during pregnancy likely account for the reduced risk of SCD in LQT2 patients during pregnancy. The marked reduction in progesterone during the postpartum period, however, likely promotes arrhythmias and SCD in these patients. Their findings also indicate that estrogen increases both trigger and sustainability of pVT, and thereby promotes major cardiac events.
He concludes that while further studies are needed in clinical trials, the clini
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