Analysis of Ventricular Repolarization by QT Measurement in Transgender People Treated With Hormone Therapy

An essential step in the care of gender dysphoria is gender-affirming hormone therapy (GAHT) combining an anti-androgen and estrogen therapy in transgender women (formerly male to female) or androgen therapy in transgender men (female to male). Several studies have shown a detrimental effect of GAHT on cardiovascular risk factors and therefore, the European Society of Endocrinology recommend an enhanced monitoring of cardiovascular risk factors in transgender population. Data on the risk of cardiac arrhythmias in transgender population are lacking, particularly on ventricular repolarization and QTc.

Indeed, sex steroid hormones and gonadotropins are known to alter the cardiac electrophysiology, as shown in various animal and human studies. From puberty to menopause, the QTc is generally longer in women than in men, translating into a higher risk of Torsade de Pointes (a peculiar form of ventricular arrhythmia) in women versus men. Recent publications have well illustrated the shortening of QTc in women in situation of biological hyperandrogenism and; QTc lengthening in hypogonadal men which was reversed by restoration of physiological eugonadal testosterone levels. Gonadotrophin's levels were positively correlated with QTc. To date, no study has focused on changes in cardiac repolarization in the transgender population and particularly on the effects of GAHT.

The aim of this study is to evaluate the impact of feminizing and masculinizing hormone treatments (GAHT) on ventricular repolarization (i.e QTc) in transgender individuals, followed at the Endocrinology department of the Haut-Leveque hospital in Pessac.

We aim to enroll consecutively (monocentric cohort) transgender individuals (on and before treatment) consulting to the endocrinology department for their usual standard of care follow-up until we include 15 transgender men and 15 transgender women with 2 QTc assessments available, one before and the other after initiation of GAHT (triplicates of 10 sec ECGs, Fridericia's heart rate correction for each time-point). This effective (n=15/group) have ≥85% power to detect a difference in QTcF≥10msec between the ECG before and after initiation of GAHT with a paired t-test (α: 0.05; standard deviation of QTc in each subgroup: 12msec; expected QTcF mean: 410msec and 400msec in women and men before GAHT, respectively, intra-individual correlation: 0.5).