Firefighters' risk of irregular heartbeat linked to number of on-the-job
fire exposures

Date:
March 23, 2022
Source:
American Heart Association
Summary:
The more fires they respond to, the higher the risk of atrial
fibrillation or AFib -- a common irregular heart rhythm -- among
firefighters, according to a survey of more than 10,000 active U.S.

firefighters. After adjusting for atrial fibrillation risk factors,
such as high blood pressure and smoking, researchers found a 14%
increased risk of atrial fibrillation for every additional five
fires fought annually.



FULL STORY ========================================================================== Among firefighters, the risk of having an irregular heart rhythm, known
as atrial fibrillation (AFib), increases with the number of fires they
respond to, according to new research published today in the Journal of
the American Heart Association, an open access, peer-reviewed journal
of the American Heart Association.


========================================================================== Compared with people in other occupations, firefighters are known
to have a disproportionately high risk of heart disease, and almost
half of fatalities in on-duty firefighters result from sudden cardiac
death -- when the heart suddenly stops beating and pumping blood
to vital organs. An increased risk of an irregular heart rhythm or
arrhythmias from the ventricles, the bottom chambers of the heart, has
been documented in firefighters, however, prior to this study, little
was known about AFib, which is an arrhythmia involving the top chambers
of the heart. According to the American Heart Association, AFib is the
most common type of irregular heartbeat with at least 2.7 million people
living with it in the United States. People with AFib have an increased
risk of blood clots, heart failure, stroke and other heart complications.

"A few years ago, I treated a local firefighter for atrial fibrillation,
and he felt dramatically better with the treatment, so he referred other firefighters to me for care, all with AFib. I decided to methodically
examine AFib in the firefighter population, as it may shed light into the
cause of atrial fibrillation in non-firefighters as well," said Paari
Dominic, M.D., senior author of the study, the director of clinical
cardiac electrophysiology and associate professor of medicine and
molecular and cellular physiology at LSU Health Shreveport in Louisiana.

Participants were recruited through five professional firefighter organizations. The study was conducted from 2018-19 among active
firefighters throughout the U.S. They completed a survey about their occupational exposure (number of fires fought per year) and about their
history of heart disease. Of the 10,860 firefighters who completed the
survey (93.5% male, and 95.5% were age 60 or younger), 2.9% of the men
and 0.9% of the women reported a diagnosis of AFib.

"Among adults in the general population younger than age 60, there is a
0.1- 1.0% prevalence of having AFib. However, among our study population,
2.5% of firefighters ages 60 or younger had AFib," Dominic said. "Of
the few respondents who were 61 or older, 8.2% reported a diagnosis
of AFib." When occupational exposure was factored in, the researchers
found a direct and significant relationship between the number of fires
fought and the risk of developing AFib. The analysis found:
* 2% of those who fought 0-5 fires per year developed AFib; * 2.3%
of those who fought 6-10 fires per year developed AFib; * 2.7%
of those who fought 11-20 fires per year developed AFib; * 3% of
those who fought 21-30 fires per year developed AFib; and * 4.5%
of those who fought 31 or more fires per year developed AFib.

After adjusting for multiple risk factors for AFib, such as high blood
pressure and smoking, researchers found a 14% increased risk of atrial fibrillation for every additional 5 fires fought annually.



========================================================================== "Clinicians who care for firefighters need to be aware of the increased cardiovascular risk, especially the increased risk of AFib, among this
unique group of individuals. The conditions that elevate their risk
further, such as high blood pressure, Type 2 diabetes, lung disease and
sleep apnea, should be treated aggressively. In addition, any symptoms
of AFib, such as palpitations, trouble breathing, dizziness and fatigue,
should be investigated promptly," Dominic said.

According to the researchers, multiple mechanisms may be involved in
the association between firefighting and AFib. "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. Exposure to these substances, especially particulate matter in
air pollution, even for a short time has been previously linked to an
increased risk of AFib. In addition, firefighters are exposed to high
physical and psychological stress together with long work hours, all of
which can increase their adrenaline levels and cause an imbalance in the 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 AFib," Dominic said.

"Studying firefighters, who personally make sacrifices for the safety of
us all, is essential to prevent disease and death in this population that
makes a big impact on the well-being of our communities," Dominic said.

The study is limited by basing the presence of atrial fibrillation and all other medical conditions on the firefighters' survey responses. However,
the researchers were able to corroborate the self-reported responses by
linking them to well-established associations between atrial fibrillation
and the presence of risk factors such as high blood pressure and sleep
apnea, suggesting that the self-reports were accurate.

The researchers are currently analyzing the survey data to investigate
the association between the annual number of fires fought and the risk
of atherosclerotic cardiovascular disease. Atherosclerosis is a buildup
of fatty deposits in the arteries that can thicken blood vessel walls
and reduce blood flow to the heart muscle, brain, kidneys or extremities.

Based on the results of this study, researchers suggest future studies systematically screen firefighters for AFib to detect asymptomatic or
new cases to evaluate the relationship between fire exposure and stroke
risk in firefighters with AFib to allow a better understanding about
which of the components of occupational exposure to fires plays a key
role in causing fibrillation. They should also examine the reluctance
of firefighters with AFib to use blood thinners. Blood thinners are a
standard treatment for AFib; however, the medication carries an added
risk of bleeding and firefighters are concerned about their increased
risk of bleeding injuries due to low-visibility firefighting situations.

Co-authors are Catherine Vanchiere, M.D.; Rithika Thirumal, M.D.;
Aditya Hendrani, M.D.; Parinita Dherange, M.D.; Angela Bennett, B.S.;
Runhua Shi, M.D., Ph.D.; Rakesh Gopinathannair, M.D.; Brian Olshansky,
M.D.; and Denise L.

Smith, Ph.D.

The research was supported by the National Institute of General Medical Sciences, a division of the National Institutes of Health.


========================================================================== Story Source: Materials provided by American_Heart_Association. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Catherine Vanchiere, Rithika Thirumal, Aditya Hendrani, Parinita
Dherange, Angela Bennett, Runhua Shi, Rakesh Gopinathannair, Brian
Olshansky, Denise L. Smith, Paari Dominic. Association Between
Atrial Fibrillation and Occupational Exposure in Firefighters Based
on Self‐Reported Survey Data. Journal of the American Heart
Association, 2022; DOI: 10.1161/JAHA.121.022543 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220323101252.htm

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