Gender-Affirming Hormone Therapy and Its Impact on Myocardial Mass and Cardiac Function: A Prospective Magnetic Resonance Cohort Study on Transgender Men and Women.

Abstract

Background and objective: Differences in cardiac parameters such as myocardial mass, left ventricular ejection fraction (LVEF), cardiac output, and brain natriuretic peptide (NT-proBNP) levels between cisgender men and women are well-established. No evidence exists regarding changes in myocardial mass or cardiac function parameters in transgender individuals undergoing gender-affirming hormone therapy (GAHT).

Methods: A prospective study enrolling transgender individuals under GAHT (20 individuals assigned female at birth (AFAB), 15 assigned male at birth (AMAB)) was conducted at the Medical University of Vienna from 2019 to 2022. A 3-Tesla electrocardiogram-gated magnetic resonance imaging measured myocardial mass, LVEF, and other cardiac function parameters before GAHT and at six-month follow-up. Myocardial lipid content was quantified using magnetic resonance spectroscopy.

Results: In AFAB, myocardial mass increased significantly after six months of GAHT from in mean (±SD) 48 (±8) g/m² at baseline to 54 (±7) g/m² at follow-up (p=0.011). AMAB showed a non-significant decrease of 4 (±14) g/m² in myocardial mass. In both groups, no significant changes were noted in LVEF, stroke volume, cardiac output, or peak filling rate. Neither testosterone (AFAB: r= -0.127, p=0.679; AMAB: r= -0.127, p=0.679) nor estradiol levels (AFAB: r= -0.154, p=0.616; AMAB: r= -0.154, p=0.616) nor BMI were related to myocardial mass at follow-up. NT-proBNP levels in AFAB were significantly reduced at follow-up (from in median (IQR) 41 (26-57) pg/mL to 19 (12-34) pg/mL).

Conclusion: Myocardial mass increased while NT-proBNP levels decreased significantly in AFAB after six months of GAHT. However, no significant changes in cardiac function were noted in AMAB and AFAB.