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WEDNESDAY, March 23, 2022 (HealthDay News)

The more blazes firefighters battle, the higher their risk for a heart rhythm disorder called atrial fibrillation (a-fib), a new study shows.

“Clinicians who care for firefighters need to be aware of the increased cardiovascular risk, especially the increased risk of a-fib, among this unique group of individuals,” said senior study author Dr. Paari Dominic. He is director of clinical cardiac electrophysiology and an associate professor at LSU Health Shreveport in Louisiana.

A-fib is the most common type of irregular heartbeat — affecting at least 2.7 million Americans. It increases the risk of blood clots, heart failure, stroke and other heart complications, according to the American Heart Association.

For the study, Dominic’s team surveyed nearly 10,900 active U.S. firefighters in 2018-2019 about the number of fires they fought each year and their history of heart disease. More than nine in 10 were male and aged 60 or younger.

In all, 2.9% of the men reported a-fib diagnosis, as did 0.9% of the women surveyed, according to a study published March 23 in the Journal of the American Heart Association.

“Among adults in the general population younger than age 60, there is a 0.1 to 1.0% prevalence of having a-fib,” Dominic noted in a journal news release. “However, among our study population, 2.5% of firefighters ages 60 or younger had a-fib.”

Of the few respondents who were 61 or older, 8.2% had been diagnosed with a-fib, he added.

After accounting for job-related exposure, researchers identified a direct and significant relationship between the number of fires fought and a-fib risk. Other studies have pointed to elevated risks for other health issues.

Rates of a-fib were:

2% among those who fought five fires or fewer per year.

2.3% among those who fought six to 10 fires a year.

2.7% among those who fought 11 to 20 fires a year.

3% among those who fought 21 to 30 fires a year.

4.5% among those who fought 31 or more fires per year.

After adjusting for multiple risk factors for a-fib, such as high blood pressure and smoking, the researchers found a 14% higher risk of a-fib for every additional five fires fought per year.

Several factors may be involved in the link between firefighting and a-fib, the study authors suggested.

“First, and foremost, are the inhalation and absorption through the skin of harmful compounds and substances produced by the combustion of materials during a fire, including particulate matter, polyaromatic hydrocarbons and benzene,” Dominic said. “Exposure to these substances, especially particulate matter in air pollution, even for a short time has been previously linked to an increased risk of a-fib.”

Dominic noted that firefighters are also exposed to great physical and psychological stress and long working hours, all of which can increase their adrenaline levels and cause an imbalance in mechanisms that maintain heart rate.

“Finally, heat stress (exposure to high temperatures) can cause an increase in core body temperature and severe dehydration, both of which increase the demand for a higher heart rate, and may subsequently trigger a-fib,” Dominic said.

He suggested that doctors should aggressively treat conditions that elevate firefighters’ risk further, including high blood pressure, type 2 diabetes, lung disease and sleep apnea.