Testosterone Levels Linked to Heart Rhythm Changes, With Risks at Both Extremes: Study - Video

Could testosterone levels influence the heart’s electrical rhythm in ways that depend on how high or low they are?

A new review published in the Journal of the Endocrine Society suggests a possible U-shaped relationship between testosterone exposure and atrial fibrillation (AF) risk in men, although evidence remains inconsistent.

Researchers reviewed studies published through May 4, 2026, including randomized trials, observational cohorts, genetic analyses and mechanistic research examining testosterone levels or testosterone replacement therapy (TRT).

The review highlighted the 2023 TRAVERSE trial, where AF occurred more frequently among men receiving transdermal testosterone gel than placebo. Other research has produced conflicting results.

Evidence examining testosterone levels suggested that AF risk may be lowest within a mid-physiological range. Analyses from the UK Biobank and ASPREE trial supported a non-linear association, with stronger evidence linking higher testosterone levels to increased AF risk in older men.

The researchers proposed that total testosterone levels around 350–550 ng/dL may correspond to the lowest observed AF risk. However, this range has not been prospectively validated as a threshold for preventing AF.

Lower levels could influence calcium handling, while higher levels may alter potassium currents, shorten cardiac action potentials and promote abnormal electrical circuits involved in arrhythmias. Testosterone exposure may also contribute to structural changes in the left atrium.

The authors stress that the review does not establish that TRT causes AF. These findings may matter when assessing men before and during long-term TRT use. Differences between studies, populations and treatment approaches make firm conclusions difficult.

Further research is needed to determine whether testosterone formulations, treatment duration and free testosterone influence AF risk.

REFERENCE: Maligireddy, A. R., Barua, S.T., Barua, R.S. (2026). Association of testosterone and testosterone replacement therapy with atrial fibrillation: an updated review, Journal of the Endocrine Society, 10(9):bvag180, DOI: 10.1210/jendso/bvag180,