Gender-affirming hormone therapy has been the subject of debate for years, and one of the questions that most concerns the medical community is its effect on the heart and blood vessels. New research published in European Heart Journal, one of the most influential cardiology journals in the world, has analyzed one of the largest cohorts to date in an attempt to answer it. The results, moreover, qualify widely held beliefs.
What the researchers did
The team, coordinated from the Amsterdam University Medical Center (Netherlands), followed for years 4,331 transgender people receiving gender-affirming hormone therapy: 2,714 transgender women (people assigned male at birth) and 1,617 transgender men (people assigned female at birth). Their data were compared with those of the general population of the same sex assigned at birth, adjusting for socioeconomic status.
The cumulative follow-up was almost 37,000 person-years. During that time, the most relevant acute cardiovascular events were recorded: myocardial infarction, stroke (cerebrovascular accident) and venous thromboembolism (formation of clots in the veins, including pulmonary embolism).
What happened in transgender women
In transgender women treated with estrogens, the risk of myocardial infarction was 50% lower than that of men in the general population (hazard ratio 0.50). The risk of stroke was similar (0.94) and, in contrast, that of venous thromboembolism was clearly higher: almost double (1.81).
In absolute figures, during the study 31 heart attacks, 74 strokes and 57 venous thromboses were observed among transgender women. In other words: estrogen therapy was not associated with a greater overall cardiovascular risk in this group, although it was associated with a specific increase in venous clots, an effect already known for these drugs.
What happened in transgender men
The picture was different for transgender men receiving testosterone. Compared with women in the general population, they had a risk of heart attack more than four times higher (4.20), a higher risk of stroke as well (1.55) and a similar risk of venous thrombosis (1.00).
In this group, 25 heart attacks, 28 strokes and 17 venous thromboses were recorded. Although the relative risk is high, the authors recall that the absolute number of events remains low, and that the comparison with the general female population starts from a very reduced risk baseline in young people.
Why the result is important
The main contribution of the study is that the cardiovascular risk of hormone therapy is not homogeneous: it depends on the direction of the treatment and on the type of event. Estrogens in transgender women did not increase the risk of heart attack or stroke, but they did increase that of venous thrombosis. Testosterone in transgender men was associated with more heart attacks and strokes than the female reference population, a finding consistent with the literature on the effect of testosterone on the cardiovascular system.
The researchers stress that the study is observational, so it does not prove causality, and that more studies are needed that adjust for other risk factors such as smoking, blood pressure or body mass index.
What it means for clinical practice
The work reinforces the idea that gender-affirming hormone therapy requires personalized cardiovascular follow-up. For transgender women treated with estrogens, monitoring of venous thrombosis risk factors (such as smoking or family history) seems especially relevant. For transgender men receiving testosterone, controlling blood pressure and lipids can help prevent the increased risk of heart attack and stroke.
In any case, the authors recall that the benefits of the therapy in terms of well-being and mental health are important, and that the goal is not to discourage its use, but to accompany it with adequate and long-term medical care.
Bibliographic reference:
van Zijverden LM, et al. Transgender persons receiving gender-affirming hormone therapy: risk of acute cardiovascular events in a Dutch cohort study. European Heart Journal 2026;47(21):2660-2669. DOI: 10.1093/eurheartj/ehaf837. PMID: 41187090.
Publication reference: European Heart Journal and PubMed.
