High testosterone levels in older males may increase risk

Atrial fibrillation occurs when the heart’s upper chambers beat irregularly. AFib is the most common type of heart arrhythmia, according to the Centers for Disease Control and Prevention (CDC). The CDC also estimates that by 2030, 12.1 million people in the U.S. will have AFib.

AFib can be dangerous because it increases the risk of blood clots, which can lead to strokes in the brain.

Non-study author Kevin Rabii, DO, a cardiologist with Memorial Herman, explained to Medical News Today:

“Atrial fibrillation is a heart rhythm abnormality that causes the top heart chambers(atria) to have erratic electrical activity and contractions. This can lead to unpleasant symptoms but it can also increase the risk of stroke and weaken the heart. It is a condition that needs to be closely monitored and treated by a cardiologist.”

While doctors can help treat AFib through certain medications and even surgical intervention, it’s also important to consider how to reduce the risk for AFib. A few common risk factors for AFib include advanced age, a family history of AFib, panic disorders, large amounts of alcohol consumption, and smoking.

The researchers of the current study wanted to examine how testosterone levels in older men affect the risk for AFib. They note that circulating testosterone levels usually decrease with age and that testosterone replacement in older men has increased.

Non-study author Mehran Movassaghi, MD, board certified urologist and director of Men’s Health at Providence Saint John’s Health Center and Assistant Professor of Urology at Saint John’s Cancer Institute in Santa Monica, CA, explained:

“As patients age, testosterone levels drop . Starting at age 30 there’s a one percent reduction in testosterone levels annually. Some patients who start off with relatively high numbers may never notice any change in their energy , their mood, or their sexual performance. However, patients generally complain of symptoms starting around the age of 40 and it’s appropriate to test their levels. It’s important to not just treat a number but actually treat symptoms that patients may be experiencing.”

Researchers utilized data from the ASPirin in Reducing Events in the Elderly (ASPREE) study. Researchers included 4,570 healthy male participants. All participants were over seventy years old and had no previous history of cardiovascular disease or thyroid cancer. About 12% of the participants had diabetes mellitus, and 75.9% had a history of high blood pressure.

The average follow-up time was 4.4 years. During the follow-up, 286 men, or 6.2%, developed AFib. Researchers could keep track of participants because of annual in-person visits and phone calls every six months.

Researchers divided serum testosterone levels into quintiles and looked at how participants’ testosterone levels related to the incidence of AFib.

The results of the study found a nonlinear relationship between testosterone levels and the incidence of AFib. They found that men with testosterone levels in the highest quintiles had a higher risk of developing AFib than those with more average levels of testosterone. They found similar results when they excluded participants who had experienced heart failure or other major adverse cardiovascular events during follow-up.

They found the association was independent of several factors, including body mass index, alcohol consumption, diabetes, and high blood pressure.

Study author Cammie Tran, BSci, MPH with Monash University, noted the following:

“We studied 4,570 initially healthy older aged men aged 70 or more years, and found that men who had higher concentrations of testosterone had nearly double the risk of developing atrial fibrillation over 4 years of follow-up, compared to men with testosterone concentrations in the middle of the range. What was interesting was that the higher risk applied to men whose testosterone concentrations were within the normal range.”

This research does have a number of limitations. First, the research relies on some level of self-reporting, which is subject to bias. The study was also observational, so it cannot prove that higher testosterone levels cause AFib.

Measurements of testosterone have circadian variation, and sample collection did not occur at a regular time of day, so this could have impacted the results. They also did not use systematic surveillance with electrocardiograms to determine the presence of AFib. Finally, researchers acknowledge the risk of confounding and possible selection bias.

Researchers note that more research is required to understand the underlying mechanisms involved in the observed relationship. Researchers also declared a few funding sources as declarations of interest.

Movassaghi noted the following limitations of the study as well:

“The study itself has several confounding issues: One [is] the data that was used was not specifically from a study design to study the problem at hand. The participants were enrolled in a clinical trial designed to study the benefits of aspirin use elderly. Given that the data was mined to look for potential causation or a relationship between testosterone levels and atrial fibrillation while statistical significance may be achieved, clinical significance is more difficult to deduce from these types of studies.”

Regardless, the study has clinical implications and areas for researchers to focus on in the future.

Tran noted the following:

“Our results suggest that atrial fibrillation may be an adverse consequence of having higher testosterone concentrations, even within the normal range. Clinicians should be aware of this risk when assessing testosterone concentrations in older men. Further research is required to investigate the possible mechanisms underlying this association, and to better understand how this impacts health in ageing men.”