Researchers culled data from the U.S. National Institute for Occupational Safety and Health and found that among on-duty firefighters, 199 fatal cardiovascular events took place between 1998 and 2012.
Of the deaths, 167 were due to heart attacks, 12 to cases of irregular heartbeat, three to strokes, and the remaining to other various cardiovascular causes. The average age of the firefighters who died was 49 years old, and they had served an average of 22 years.
Study co-author Dr. Aveen Saed and colleagues also collected basic information about each firefighter. This included what they were doing at the time of death; their age range; health conditions they had, such as high blood pressure and high cholesterol; and if they were taken to a hospital.
The researchers rated the activities the firefighters were doing right before a cardiovascular event as either "light to moderate," or "vigorous."
Driving and getting out of a vehicle were considered light tasks, while lugging heavy hoses, rescuing someone and running were labeled vigorous, explained Saed, a research fellow at Zeenat Qureshi Stroke Institute in St. Cloud, Minn.
The study found that 148 of the incidents took place after vigorous activity that took about 33 minutes, on average. Eighty-eight of the firefighters were actively fighting a fire, and at least 61 were responding to an emergency.
Then the researchers looked at personal heart risk factors for the 148 firefighters. Ninety-four had high cholesterol and 93 had high blood pressure, while 42 were smokers, 22 had diabetes and 46 had a family history of heart disease.
Of 51 firefighters performing light to moderate physical activity, 38 had high blood pressure, 34 had high cholesterol and 20 were smokers. In addition, seven had diabetes and 11 had a family history of heart disease.
"Our study brings awareness of the fact that these events are occurring, and they're occurring because of the activities the firefighters were involved in," Saed said. "But also, we have to look at the fact that a majority of these patients had other [conditions] such as high blood pressure, high cholesterol, and some were smokers."
She said the study results suggest that people in emergency professions and other fields of work that involve heavy labor or episodes of vigorous work should have regular health checks. "Firefighters should be aware of their risk factors if they are involved in vigorous activities on the job. Get regular check-ups and have their cholesterol and sugar levels checked, along with EKG stress tests," Saed advised.
Dr. Chip Lavie is medical director of cardiac rehabilitation and preventive cardiology at the John Ochsner Heart and Vascular Institute, in New Orleans. He said, "It is well known that high-intensity exercise as well as high mental stress are both associated with being triggers for acute cardiovascular events."
Even in someone who is well trained, vigorous physical exertion may increase the risk of a major cardiac event, said Lavie, who was not involved with the study.
"However, if such a person regularly performs vigorous exercise, their risk of cardiac event for the other 22 hours in the day may be reduced by nearly 50 percent, so the net effect is very beneficial," Lavie said.
Firefighters are probably more physically active than the general public, he said, but there may be significant individual differences in overall fitness and in cardiovascular risks among firefighters.
"High-risk individuals may reduce their risk by maximizing regular exercise and fitness, as well as by therapies such as baby aspirin, lipid [cholesterol] treatment, especially statins when appropriate," along with treatment to prevent high blood pressure, Lavie said.
The researchers will present their study findings at the American Academy of Neurology's annual meeting, April 26 to May 3 in Philadelphia. Research presented at meetings should be viewed as preliminary until published in a peer-reviewed journal.
To learn more about the warning signs of a heart attack, visit the American Heart Association.