JAMA Netw Open

Hormone therapy linked to QT interval changes in transgender patients

August 1, 2025

Study details: This prospective cohort study in France enrolled 120 transgender adults (64 transgender men, 56 transgender women) to assess the impact of gender-affirming hormone therapy (GAHT) on cardiac repolarization. Transgender men received injectable testosterone, while transgender women received transdermal estradiol and primarily oral cyproterone acetate. Electrocardiographic parameters (QTc, T-wave maximal amplitude [TAmp], and QT peak [QTp; distance between Q onset and T peak]) and circulating sex hormones were measured before and after GAHT initiation.

Results: Testosterone therapy in transgender men was associated with QTc shortening (mean decrease, 17 ms), while androgen deprivation in transgender women led to QTc prolongation (mean increase, 20 ms). No participant exceeded a QTc of 480 ms or had a QTc change >60 ms. QTc changes correlated with total testosterone and prolactin levels. The direction of changes in QTp and TAmp mirrored those of QTc, but in opposite directions for transgender men and women.

Clinical impact: Findings demonstrate that GAHT induces QTc changes in transgender individuals, recapitulating the sexual dimorphism observed in cisgender adults. While no clinically significant arrhythmias were observed, the potential for QTc prolongation—especially in the context of concomitant QT-prolonging medications—warrants attention in this growing population.

Source:

Grouthier V, et al. (2025, July 1). JAMA Netw Open. Transgender-Affirming Hormone Therapies, QT Prolongation, and Cardiac Repolarization. https://pubmed.ncbi.nlm.nih.gov/40736733/