|Aerobic capacity stress test performed during annual wellness medical at the Calgary Fire Department Wellness Centre. Photo courtesy Calgary Fire Department
Everyone has heard stories of beer-league hockey players with no apparent history of heart problems collapsing on the ice from heart attacks. The same thing can happen to firefighters. This new test, called Microvolt T-Wave Alternans, or MTWA, can pinpoint a firefighter’s – or a hockey player’s – risk for heart attack. Essentially, MTWA is a subtle heart rhythm abnormality that is a specific marker of arrhythmic (heart rhythm) vulnerability and risk of sudden cardiac arrest.
A pilot project at the Freeport Fire Department in Maine in the fall of 2010 determined that the nine volunteer members are heart healthy but picked up signs of potential issues with blood pressure and diabetes.
“I have been very concerned about my firefighters’ heart health, so when I found out [Dr. Gerber] had some ideas that would help me look out for heart attack risk, I was intrigued,” Freeport Fire Chief Darrell Fournier said in a phone interview. Fournier heard Gerber speak at a Rotary Club luncheon and followed up with him about the testing for his crews.
Gerber, an associate professor at Harvard Medical School, is at the forefront of this heart-testing research with a company called Cambridge Heart and its MTWA. The treadmill stress test looks for subtle abnormalities in a heartbeat pattern; the test has been shown to accurately predict vulnerability to heart attack – even in a fit, active people who are of ideal weight.
Gerber says the MTWA test is probably the most accurate predictor of people at risk for heart attacks. The test is available in Canada through the University of Calgary hospital and the Hospital for Sick Kids in Toronto. Until the MTWA test is more widely available, experts recommend that firefighters have regular medical checkups and any other kind of cardio screening available through their physicians or fire departments.
“Fortunately, none of the nine firefighters we tested showed these markers,” Gerber said of Freeport’s crew of volunteer. “But they all had signs of having potential issues with pre-high blood pressure and even pre-diabetes, so the testing gave us a heads-up before things became more serious,” he said.
The testing builds on a wealth of research into why firefighters are so prone to heart attacks. A 10-year study completed in 2010 by the Libin Cardiovascular Institute of Alberta at the University of Calgary followed 1,574 firefighters. At the outset and every six months for 10 years, each firefighter’s brachial artery (in the arm) was measured using ultrasound to monitor its functionality. This data was compared with the ongoing health of the participants, including their heart attack history.
“The results indicate that in addition to the function of the heart, the function of blood vessel linings also contributes to coronary heart disease,” says Ian Crosby, fitness and wellness co-ordinator for the Calgary Fire Department. “Researchers found that when the linings of arteries became irregular, or sticky, they were more likely to accumulate cholesterol, which could then trigger a coronary episode, heart attack or stroke.”
According to the NFPA in its report U.S. Firefighter Fatalities Due to Sudden Cardiac Death 1995-2004, of the 1,006 on-duty firefighter fatalities over the 10-year period, 440 – or 43.7 per cent – fell into the category of sudden cardiac death. The report said the largest proportion of the victims experienced cardiac symptoms during fire ground operations – 155 deaths, or 35.2 per cent.
Because Canada does not have a national fire commissioner’s office to compile statistics, the Canadian fire service does not know if firefighter deaths follow the same pattern, says Barry Malmsten, executive director of the Ontario Association of Fire Chiefs.
“However, given the similarities in both countries’ operating environments and anecdotal information, it seems reasonable to assume that heart attacks are the No. 1 killer here as well.”
Calgary’s Crosby agrees. “In fact, firefighters are three times more prone to heart attacks than people working on other occupations,” he says While many older, overweight, unfit people – and firefighters – can be prone to heart attacks from overexertion, there are subtle factors (genetic factors and others) that can lead to fit people dying of cardiac arrest while many overweight, sedentary, yet stressed, people live to a ripe old age.
Dr. Stefanos Kales is an expert on cardio health and has done substantial research on U.S. firefighter fatalities.
“The main factors that make firefighters over 40 more prone to heart attacks is being unfit, carrying too much weight, having a history of heart disease and/or an excess of heart disease risk factors, and then having to take part in strenuous work,” Kales said in a phone interview.
Kales said previous studies by his team show that 25 to 30 per cent of firefighters who died of cardio issues had already been diagnosed with heart disease and almost 60 per cent had cardiac enlargement at autopsy, which usually indicates chronic uncontrolled high blood pressure. Additionally, about 40 per cent of those who died were smokers.
More to the point, in a 2007 paper that Kales and his associates published in the New England Journal of Medicine, they proved statistically that cardio-related deaths were between 10 times and more than 100 times more likely to happen during fire suppression than during non-emergency duties. Heart death risks were also elevated in other emergency activities such as alarm response and alarm return, as well as physical training.
The team also found that many new and veteran firefighters are out of shape, and that more than 70 per cent of U.S. fire departments lacked programs that promote fitness and health.
“Most fire departments do not require firefighters to exercise regularly, undergo periodic medical examinations or have mandatory return-to-work evaluations after a major illness,” Kales said.
To make matters worse, Crosby says the physical demands placed on firefighters are often greater than the human body is designed to bear.
“It is not uncommon for firefighters to have their heart rates exceed their predicted maximums for 25 minutes or longer due to their bodies pumping adrenalin at the fire scene,” he says.
“The human body was never meant to operate at this adrenalin level for this time period. We cannot even simulate these conditions on a treadmill to see what they mean, because it is impossible to trigger adrenalin for such a long time period in the lab.”
Wearing heavy protective gear makes it difficult for the body to vent excess heat, while breathing dry, compressed air can stress the cardiovascular system, Crosby says. The result is a perfect storm of factors that can swamp firefighters who are already vulnerable to heart attacks.
While many Canadian departments are adopting fitness and wellness programs and working with firefighters to improve their health and fitness, Freeport’s Chief Fournier says firefighters need to shoulder some of the responsibility.
“After the work I’ve done with Dr. Gerber, I’ve learned to stop packing on carbs at fast-food places,” says Chief Fournier. “What I put into my body matters, both in terms of weight and the health of my heart and arteries.”
Many health and wellness programs, including the International Association of Fire Chiefs Wellness/Fitness Initiative – which has been adopted in Calgary and other departments – ensure that firefighters have regular medical exams that include cardiac testing. Crosby says it is not enough for firefighters to work out and eat right if they have an underlying condition that can make them vulnerable to heart attacks. Knowing that heart rhythm problems exist can allow doctors to treat firefighters with drugs and, if need be, install pacemakers to keep their hearts on beat.
In addition, he says, departments need to ensure that older firefighters with health issues feel safe telling management about health concerns and that jobs are not lost as a result; otherwise, the people who need help most will seek it the least.
“There are many, many things that can be done to help reduce the rate of heart attacks in firefighters,” says Chief Fournier. “Improving fitness, changing diet and detecting risk factors for heart disease will save the lives of our people and the public they protect. It will also make a real difference to their families, who won’t have to be told that their father/husband died on the fire scene. This is all within our reach; we just have to do it.”
James Careless is a freelance writer based in Ottawa and a frequent contributor to Canadian Firefighter and EMS Quarterly.