It seems like we can’t get away from advertisements about testosterone replacement therapy (TRT). But is it right for every man? Both low and high testosterone levels, as well as TRT, can influence cardiovascular function and may be associated with heart rhythm changes, including atrial fibrillation. Because symptoms of low testosterone overlap with other conditions, proper diagnosis requires both lab testing and clinical evaluation.
Updated for 2026
With the proliferation of body hacking advice across the internet and podcasting world, a lot of men’s ears are perking up about low testosterone. Advertisements about testosterone replacement therapy (TRT) are all over the place. By how often it is advertised, you’d be forgiven for thinking it is a ubiquitous male problem.
Low testosterone has been implicated in many concerning male health issues, and frequently touted as a panacea for the drop in activity and muscle building that many men experience in middle age and beyond. But because the symptoms of “Low-T” are non-specific, it’s best to talk to a doctor to make sure it’s an appropriate therapy.
TRT has not been implicated in increases in major cardiovascular events, like heart attacks.1 But can testosterone therapy affect heart rhythm, and in particular, Afib?
Low or High Testosterone is Not Ideal
The short answer is yes. Testosterone replacement therapy can cause heart rhythm concerns and even Afib.2
Before even taking TRT, low or high testosterone levels have a distinct effect on the hormonal balance of the male body and blood flow. For example, low testosterone (male hypogonadism) can result in low libido, fertility issues, erectile dysfunction, loss of muscle mass, hair, and bone density, and negatively impact energy and mood. Low levels can also be linked to stiff arteries and increased risk of peripheral artery disease (PAD).3 Too much testosterone, which is rare naturally and really only occurs with supplementation, can shrink the testicles, cause acne and severe mood swings or aggression, and strain the cardiovascular system. In particular, too much can make blood more viscous, increase blood pressure and clotting risk, and, in turn, increase the chance of having a heart attack. TRT can increase testosterone and also the likelihood of developing Afib.4
It is worth noting that low testosterone may also be associated with longer QT intervals5, and it’s possible that TRT could shorten those intervals. But it doesn’t mean hormone therapy is a treatment for arrhythmia risk or long QT syndrome.
Be sure to speak to your electrophysiologist before starting or modifying a testosterone replacement routine, especially if you have suspected or diagnosed rhythm issues.
Defining “Low-T”
Defining low testosterone requires a visit to the doctor and a few diagnostic tests; it is not diagnosed or treated based on symptoms alone.
For one, low testosterone is often misdiagnosed and can be used as an excuse for poor lifestyle habits. Symptoms of low testosterone (fatigue, low libido, weight gain, low mood) overlap heavily with obesity, poor sleep, inactivity, and metabolic syndrome, and because of that overlap, it’s important to distinguish true hypogonadism from lifestyle-related metabolic changes.
Second, blood levels are usually benchmarked against a younger man’s normal testosterone results. In other words, the reference ranges used are not always perfectly adjusted for age-related hormonal changes, which can complicate interpretation in older men. Testosterone levels tend to decline gradually with age, so what is typical for a 60-year-old is very different from what’s normal for someone much younger.
Most urologists rightly diagnose low testosterone based on both consistent symptoms and repeated low morning testosterone levels. Diagnosis of hypogonadism is not symptom-only.
As a frame of reference, normal testosterone levels can range anywhere from roughly 300 ng/dL to 1000. Rather than focusing entirely on concerns about testosterone levels, treatment is based on confirmed biochemical deficiency plus compatible symptoms. Because of individual variability in health profiles, men can be at the 250 level who feel fantastic, and others with much higher testosterone who feel terrible. Other conditions can mimic low testosterone (sleep apnea, depression, obesity, chronic illness), so treating symptoms alone without confirming hormonal abnormality can lead to misdiagnosis or inappropriate hormone therapy.
Once TRT is begun, monitoring is essential. The goal is to administer the least amount for the greatest effect, and reduce the risk of complications.
So What’s the Answer?
Protecting heart health and maximizing testosterone production, even when on TRT, can also happen at home. A man can often do plenty to reduce the risk of new or worsened heart rhythm issues like Afib, including losing weight, exercising, sleeping well (so important!), and more. As we age, we might become less active or tend to lose some of the good habits we had as younger folks. That can, in turn, cause a more rapid decline in testosterone in middle age.
Making simple lifestyle changes is the easiest and lowest-risk way to increase testosterone production and improve cardiovascular health. For men who are struggling with Low-T symptoms, a trip to the urologist is a great place to start. And if you experience symptoms that sound more like a heart rhythm disturbance, like a fast, fluttering, or pounding heartbeat (palpitations), chest pain, shortness of breath, fatigue, dizziness, and weakness, a consultation with an electrophysiologist can also be helpful.
If you are experiencing a medical emergency, dial 911 and go to your nearest emergency room.
Note: There are currently no FDA-approved testosterone therapies specifically indicated for women in the United States. In cases of postmenopausal women experiencing Hypoactive Sexual Desire Disorder (HSDD), some doctors will prescribe testosterone off-label and at much smaller doses than men. For more about hormone replacement therapy for women and heart health, click here.
Dr. Tordini is a part of Florida Medical Clinic Orlando Health
- Hackett G. I. (2025). Long Term Cardiovascular Safety of Testosterone Therapy: A Review of the TRAVERSE Study. The world journal of men’s health, 43(2), 282–290. https://doi.org/10.5534/wjmh.240081.
- Solan, M. (2023, October 1). Testosterone therapy may be safe for men at risk for heart attack and stroke. Harvard Health. https://www.health.harvard.edu/mens-health/testosterone-therapy-may-be-safe-for-men-at-risk-for-heart-attack-and-stroke.
- Harvard Health. (2010, March 1). Testosterone and the heart. Harvard Health Publishing. https://www.health.harvard.edu/heart-health/testosterone-and-the-heart.
- Solan, M. (2023, October 1). Testosterone therapy may be safe for men at risk for heart attack and stroke. Harvard Health. https://www.health.harvard.edu/mens-health/testosterone-therapy-may-be-safe-for-men-at-risk-for-heart-attack-and-stroke.
- Venkatakrishnan, A., Srinivasan, D., Malik, A., Hazareh, M., Nizami, M. A., Chen, J. Y., & Ng, F. S. (2026). Effect of estrogen and testosterone on cardiac electrophysiology and atrial fibrillation. Heart Rhythm O2, 7(2), 393–403. https://doi.org/10.1016/j.hroo.2025.11.007.
