Low and high testosterone linked to arrhythmia — ScienceAlert
Researchers at the University of Kansas Medical Center, in a review of existing studies, found an association between low and high testosterone levels and an increased risk of atrial fibrillation. However, a causal relationship between the hormone and the heart rhythm disorder has not yet been established, ScienceAlert reports.
What is known about the risk
Atrial fibrillation occurs when the upper chambers of the heart lose their coordinated contraction rhythm. It can cause sensations of rapid or irregular heartbeat, fatigue and dizziness, although some people have no symptoms. This condition also increases the risk of stroke, and some patients require long-term use of blood-thinning medication.
The authors of the review, published in the Journal of the Endocrine Society, analyzed human studies and laboratory work. Earlier population studies, including the Framingham Heart Study, linked lower testosterone levels to a higher risk of atrial fibrillation in certain age groups.
In one study involving 4,570 older men without prior cardiovascular disease, the two highest testosterone-level groups had approximately twice the risk of atrial fibrillation as the middle group. Over a median follow-up period of 4.4 years, the condition developed in 286 participants. The study did not record a statistically significant increase in risk for the lowest hormone level.
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Data on replacement therapy
The 2023 randomized TRAVERSE trial involved 5,246 men with low testosterone levels and existing cardiovascular disease or an elevated risk of developing it. They were assigned a testosterone gel or a gel without testosterone. Atrial fibrillation occurred in 3.5% of participants in the testosterone group and 2.4% in the comparison group. At the same time, the study found no increase in the primary composite outcome, which included cardiovascular death, nonfatal heart attack and nonfatal stroke.
Laboratory data indicate that low and high hormone levels may affect the heart through different pathways: a low level may disrupt calcium regulation in heart cells, while a high level may alter potassium currents involved in generating the heart's electrical signals.
Researchers advise assessing heart health and other risk factors before starting therapy, including obesity, high blood pressure, alcohol consumption and sleep apnea. At the same time, a meta-analysis of 106 randomized trials published in 2024 found no statistically significant increase in the incidence of atrial fibrillation when trials other than TRAVERSE were considered collectively. The review authors note that the benefit of maintaining hormone levels in the middle of the normal range for reducing the risk of arrhythmia has not yet been proven.
