SAT645 Cardiac Autonomic Modulation In Transgender Men Under Gender-affirming Hormone Therapy

Disclosure: R.M. Allgayer: None. L. Horos Bueno: None. R. Silveira Moraes Filho: None. P. Spritzer: None. Heart hate variability (HRV) spectral indices are associated with age and sex. Men have higher frequency amplitudes, with lower HRV than women, suggesting greater sympathetic activity and, theoretically, greater susceptibility to fatal arrhythmias and development of coronary disease, which may be related to higher testosterone levels in men. Scarce data are available on the sympathovagal balance in transgender men. The objective of the present study was to assess whether heart rate variability (HRV) at rest and during sympathetic stimulation is disturbed in healthy transgender men in comparison to cisgender women. A cross-sectional study was conducted at a university hospital with the evaluation of eleven transgender men under testosterone treatment (for at least 6 months) and eleven age- and BMI-paired cisgender women, by a sample size calculation(1). Patients with established cardiovascular disease, hypertension, diabetes, and smoking were excluded. Patients who were using medications other than testosterone that could have an impact on heart hate variability were also excluded. Anthropometric, metabolic, hormonal assessment and analysis of HRV indices (time and frequency domain HRV indices) at rest and after a mental stress test were measured. For HRV analysis, participants underwent a 30-minute electrocardiogram recording with a SEER Light digital. For HRV testing, participants were instructed to abstain from caffeine, stimulants, alcohol, and heavy exercise for 24 hours. In the color-word stress test, the subject is shown the printed names of colors on screens of a different color and is asked to name the color of the screen rather than the word. The median age was 23 [22-26] years in transgender men and 24 [22-26] in cisgender women. Mean BMI was 22.32 (±3) in TM and 21.82 (±2.81) in CW. Systolic blood pressure of transgender group was higher than cisgender group, 113.45 (11.09) versus 101.18 (8.08) mmHg, p<0.008. Other metabolic parameters such as fasting glucose, HOMA-IR, lipids, and diastolic blood pressure did not differ between groups. At rest, no differences in HRV were found between groups. However, during sympathetic stimulation with the mental stress test, transgender men, compared to cisgender women, had a significantly lower increase in normalized low frequency (LF) units (ΔLF= 0.19 ±0.04 vs. ΔLF= 0.35 ±0,05; p=0.025) and LF-to-HF ratio (ΔHF/LF= 1.7 ±0,4 vs. 5.7 ±0,76; p<0,001) in response to the mental stress test, respectively. In conclusion, the present results suggest that transgender men have impaired autonomic modulation in response to sympathetic stimulation when compared to cisgender women. The difference in sympathovagal HRV control after stress testing could reflect the effects of testosterone treatment on cardiac autonomic modulation.(1) Resmin E, et al. Sympathovagal imbalance in transsexual subjects. J. Endocrinol. Invest. 2008; 31: 1014-1019. Presentation: Saturday, June 17, 2023