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Class III antiarrhythmic drugs are a group of medications that can prolong action potentials in the heart. They achieve this by blocking potassium channels or enhancing inward currents from sodium channels. However, these drugs have a unique property of "reverse use-dependence," which is most pronounced at slower heart rates and can lead to torsades de pointes—a specific type of arrhythmia. However, it is essential to note that excessive QT interval prolongation—a measure of...

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Related Experiment Video

Updated: Sep 13, 2025

Establishment of Rat Models Mimicking Gender-affirming Hormone Therapies

Establishment of Rat Models Mimicking Gender-affirming Hormone Therapies

Published on: January 10, 2025

Transgender-Affirming Hormone Therapies, QT Prolongation, and Cardiac Repolarization.

Virginie Grouthier^1,2, Marie Matamala¹, Antoine Tabarin¹

¹Department of Endocrinology, Diabetes and Nutrition, Centre Hospitalier Universitaire de Bordeaux, Haut-Leveque Hospital, F-33604 Pessac, France.

JAMA Network Open

|July 30, 2025

Summary

Gender-affirming hormone therapies (GAHTs) impact cardiac repolarization differently in transgender men and women. Testosterone shortened QTc in transgender men, while antiandrogen therapy prolonged it in transgender women, mirroring cisgender sexual dimorphism.

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Published on: March 24, 2023

Area of Science:

Cardiology
Endocrinology
Transgender Health

Background:

Gender-affirming hormone therapies (GAHTs) involve androgens for transgender men and antiandrogens with estrogens for transgender women.
Cardiovascular outcomes of GAHTs are not well-studied, particularly effects on cardiac repolarization.

Purpose of the Study:

To investigate the association between GAHT and cardiac repolarization alterations in transgender individuals.
To analyze electrocardiographic changes in relation to hormone levels during GAHT.

Main Methods:

A prospective cohort study of 120 transgender individuals (64 men, 56 women) in France from 2021-2023.
Electrocardiographic parameters (QTc, TAmp, QTp) and circulating sex hormones were assessed.
Nonlinear mixed models were used to analyze associations, controlling for confounding factors.

Main Results:

Testosterone therapy in transgender men shortened QTc and QTp, and increased TAmp.
Antiandrogen therapy in transgender women prolonged QTc and QTp, and decreased TAmp.
QTc changes mirrored sexual dimorphism observed in cisgender populations.

Conclusions:

GAHT significantly impacts cardiac repolarization in transgender individuals.
Testosterone and antiandrogen therapies induce opposite effects on QTc, QTp, and TAmp.
These findings highlight the need for attention to GAHT's cardiovascular effects, especially in those also taking QTc-prolonging drugs.