A recent study investigated the link between testosterone levels and the risk of atrial fibrillation (AFib).
- Atrial fibrillation (AFib)
affects millions of people in the United States alone. Increased age is
one risk factor for AFib, but many other risk factors are not as well
understood.
- Researchers are interested
in what additional factors increase someone’s chances of developing AFib.
- Results of a recent study
found that among older men, higher levels of testosterone are associated
with an increased risk for AFib.
Addressing cardiovascular
problems in older adults is a critical area of health. Atrial
fibrillation (AFib) is a common and problematic
heart rhythm, and researchers are interested in understanding its
risk factors.
A study published
in eClinicalMedicine examined the association
between testosterone levels and AFib in over 4,500 male
participants. Researchers found that older men with higher levels of circulating testosterone were at an
increased risk for AFib. The results highlight the importance of proper
monitoring for AFib and testosterone levels in older men.
As research moves
forward, doctors may need to consider the risks of AFib when helping older men
evaluate the risks of testosterone therapy.
Atrial
fibrillation: Dangers and risk factors
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.
How
do testosterone levels affect risk of AFib?
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.”
Study
limitations and continued research
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.”
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