IPM Take
Firefighters are screened because everyone already knows their work can put extraordinary pressure on the cardiovascular system. The uncomfortable question raised by new research is whether screening is looking for enough of the right things.
A JACC: Advances analysis of more than three decades of US firefighter fatalities found that cardiac causes accounted for 43% of 3,401 on-duty deaths. During the main pre-pandemic analysis period, total firefighter fatalities fell, yet cardiac deaths became progressively more prominent as a share of those fatalities.
That distinction matters. The study does not show that the absolute incidence of cardiac death among firefighters increased because the researchers did not have firefighter person-years as the denominator. It shows that cardiovascular prevention has not improved as quickly as other aspects of firefighter mortality.
The autopsy findings are where the policy question becomes sharper. Obstructive coronary artery disease was common, appearing in 57% of available autopsies, but left ventricular hypertrophy was substantially more common, appearing in 79%. Among firefighters with left ventricular hypertrophy, 43% had no obstructive coronary disease.
Current firefighter medical standards appropriately pay substantial attention to coronary risk. The new study does not argue that this should stop. Instead, it asks whether coronary-focused screening is sufficient when fatal vulnerability may also involve structural myocardial disease, fibrosis and an arrhythmogenic substrate that can become dangerous under the enormous physiological stress of fire suppression.
There is no validated replacement screening pathway yet, and indiscriminately adding advanced imaging would create its own risks of false positives, unnecessary restrictions and cost.
But occupational screening has a basic obligation: it should be designed around what is actually killing the workforce.
The autopsy room may now be telling policymakers that the current answer is more complicated than blocked arteries.
Executive Summary
A brief report published in JACC: Advances examined long-term trends in on-duty cardiac deaths among US firefighters and reviewed autopsy findings to determine whether the pathology associated with fatal events aligns with existing cardiovascular prevention strategies.
Researchers analysed 3,401 on-duty firefighter fatalities recorded by the US Fire Administration between 1990 and 2025, with an average age of approximately 46 years. Overall, 1,474 deaths, or 43%, were classified as cardiac.
Because COVID-19 distorted mortality during the pandemic, the primary trend analysis focused on 1999 through 2019 and included 2,097 fatalities. Although total firefighter deaths declined during that period, the odds that an on-duty fatality was cardiac increased by approximately 2.2% per year.
Among career firefighters, the increase was approximately 3.7% per year, while no statistically significant temporal trend was observed among volunteer firefighters. Importantly, the statistical difference between the career and volunteer trends itself did not reach significance, so the findings should not be interpreted as proof that the two groups experienced fundamentally different trajectories.
The study compared these proportional mortality trends with the US population, where cardiac deaths as a proportion of overall mortality declined by approximately 1.3% annually over the same period. The comparison provides context rather than a direct comparison of incidence.
Researchers then reviewed 803 firefighter fatality investigations conducted through the National Institute for Occupational Safety and Health programme between 1997 and 2022. Autopsy information was available for 282 cases, or 35%.
Among those autopsies, 79% showed left ventricular hypertrophy, 57% showed obstructive coronary artery disease, and 44% involved ventricular tachycardia or ventricular fibrillation. Critically, 43% of firefighters with left ventricular hypertrophy did not have obstructive coronary disease.
The prevalence of coronary disease remained relatively stable over time in the autopsy series, while left ventricular hypertrophy became increasingly common, particularly among cardiac deaths and deaths associated with ventricular arrhythmia.
The findings are hypothesis-generating rather than sufficient to change screening standards. Autopsies were available for only a subset of deaths, the study examined proportional mortality rather than population incidence, and structural enlargement in physically trained firefighters can be difficult to distinguish from physiological athletic adaptation.
The authors argue that prospective studies incorporating cardiac magnetic resonance, arrhythmia surveillance and occupational exposure measurements may be needed before screening pathways can be redesigned.
Why it matters
- HTA bodies: The study raises a classic screening problem: detecting more abnormalities is not necessarily the same as preventing more deaths. Cardiac magnetic resonance, coronary CT and rhythm monitoring could theoretically identify pathology missed by ischemia-focused testing, but any expansion would require evidence of diagnostic yield, clinical actionability, false-positive rates and outcome benefit before population-wide implementation.
- Payers: Firefighter cardiovascular screening sits at the intersection of occupational medicine and preventive cardiology. If structural myocardial disease proves to contribute meaningfully to sudden death, payers and public employers may face pressure to fund more advanced evaluation for selected high-risk personnel. The economic case will depend heavily on targeting, because universal advanced imaging could generate substantial downstream testing without evidence that it improves outcomes.
- Industry / innovation partners: There is a growing opportunity for imaging, wearable rhythm monitoring and risk-stratification technologies designed specifically for high-risk occupational populations. The central challenge will be avoiding systems that simply detect more abnormalities. Useful technologies will need to distinguish pathological hypertrophy and arrhythmic substrate from the physiological remodelling expected in a fit workforce.
A firefighter can pass a fitness test, perform well under exertion and still carry a heart that becomes vulnerable when the alarm sounds.
That possibility sits at the centre of new research examining why cardiovascular disease continues to account for such a large share of firefighter deaths despite decades of improvements in occupational safety.
The study, published in JACC: Advances, begins with an apparent contradiction. US firefighters are dying less often on duty overall, yet when an on-duty death does occur, it is increasingly likely to be cardiac.
Across 3,401 fatalities recorded between 1990 and 2025, 43% were attributed to cardiovascular causes. When researchers focused on the period from 1999 through 2019 to avoid the distortion caused by pandemic mortality, total deaths continued to fall, but the odds that a fatality was cardiac increased by roughly 2% each year.
That does not mean the individual firefighter’s annual probability of cardiac death rose by 2%.
The study did not calculate incidence across the entire firefighter workforce, because its denominator was on-duty deaths rather than firefighter person-years. What increased was the share of fatalities attributed to cardiac causes.
That distinction is more than methodological housekeeping. It changes the policy interpretation.
Fire departments have become better at preventing many forms of occupational death. Protective equipment, training, incident management and other safety measures have contributed to a long-term decline in line-of-duty mortality. Cardiovascular prevention appears not to have kept pace to the same degree.
The latest US Fire Administration data underline why the problem remains urgent. In provisional data for 2025, cardiovascular events accounted for 48 of 81 on-duty firefighter fatalities.
The conventional explanation for much of this risk has been coronary artery disease, and there are good reasons for that focus. Fire suppression can place extraordinary demands on the cardiovascular system as heavy exertion occurs alongside heat exposure, dehydration, sympathetic activation and psychological stress. In someone with significant coronary atherosclerosis, that combination can become dangerous quickly.
Current occupational-health standards therefore place strong emphasis on identifying conventional cardiovascular risk and, in selected higher-risk personnel, further evaluation for coronary disease.
The new autopsy data suggest that this remains necessary.
They also suggest it may not be sufficient.
Among the 282 deaths for which detailed autopsy information was available, obstructive coronary artery disease was found in 57%. That is an important burden and provides no justification for weakening coronary prevention.
But left ventricular hypertrophy was found in 79%.
Even more strikingly, 43% of firefighters with left ventricular hypertrophy did not have obstructive coronary disease.
Those findings shift the clinical question from the arteries toward the myocardium itself.
Left ventricular hypertrophy describes thickening of the muscular wall of the heart’s main pumping chamber. It can emerge in response to chronic hypertension and other pathological stressors, and it has long been associated with arrhythmia and cardiovascular risk.
But in firefighters, interpretation becomes unusually difficult because exercise can remodel the heart too.
A physically trained person can develop larger chambers and greater myocardial mass as a normal adaptation to repeated cardiovascular demand. In an occupational group whose job itself requires significant physical capacity, a thicker or larger heart cannot automatically be labelled diseased.
That is exactly why standard screening can become complicated.
A conventional echocardiogram may identify increased wall thickness, but the test cannot always answer the question that matters most: is this benign physiological adaptation or pathological remodelling carrying an arrhythmic risk?
The study’s authors therefore do not simply argue for more echocardiography.
In fact, they explicitly caution that standard echocardiography may have limited ability to solve the problem in such a physically active workforce because physiological training adaptation can resemble early structural disease.
The potential blind spot is more subtle.
Existing cardiovascular prevention is well equipped to ask whether the coronary arteries are likely to become ischemic during exertion. Exercise stress testing with imaging can identify some forms of coronary disease and remains an important component of risk assessment in selected firefighters.
It may be less capable of identifying diffuse myocardial fibrosis, pathological hypertrophy or another substrate capable of generating a fatal ventricular arrhythmia under extreme physiological stress.
That distinction matters because sudden cardiac death often requires more than a trigger.
The physiological stress of firefighting can provide the trigger: heat, dehydration, catecholamine surges and maximal exertion can all destabilise the cardiovascular system.
But the heart may also require a vulnerable substrate.
The autopsy findings raise the possibility that, in some firefighters, structural myocardial disease provides that substrate even when obstructive coronary disease is absent.
Ventricular tachycardia or ventricular fibrillation was documented in 44% of the autopsy cases. Among deaths associated with those malignant ventricular rhythms, the prevalence of left ventricular hypertrophy increased substantially over time.
That association does not prove that the hypertrophy caused the arrhythmia.
The data come from people who had already died, and autopsy findings cannot reconstruct the entire biological pathway leading to the event. Hypertension, obesity and occupational exposures may all contribute, while the available reports varied in their level of detail.
Even after adjustment for several conventional risk factors, however, the temporal signal persisted.
This is where the findings begin to challenge the design of occupational cardiovascular screening.
The National Fire Protection Association’s current NFPA 1580 standard, which consolidated the former NFPA 1582 medical standard with other firefighter health and wellness standards, provides the framework for occupational medical programmes. Firefighters are expected to undergo regular medical evaluation, with additional cardiovascular assessment according to risk.
The study does not demonstrate that this framework fails.
It suggests that the biology producing fatal events may be broader than the biology around which some screening strategies have traditionally been organised.
That distinction is crucial because the obvious response, simply adding more tests, could create another problem.
Cardiac magnetic resonance can characterise myocardial tissue and identify fibrosis far better than standard echocardiography. Extended rhythm monitoring can detect arrhythmias that a resting electrocardiogram misses. Coronary CT can identify subclinical atherosclerosis.
But testing a healthy workforce with increasingly sensitive technology inevitably identifies more abnormalities.
Some will matter.
Some will not.
And in firefighters, the consequences of an uncertain abnormality can include additional testing, anxiety, occupational restrictions or questions about fitness for duty.
A screening programme that finds more disease but cannot distinguish dangerous pathology from harmless adaptation could generate harm of its own.
The next policy question is therefore not whether every firefighter should receive a cardiac MRI.
The evidence does not support that.
The question is whether researchers can identify a subgroup in whom deeper myocardial evaluation meaningfully improves risk prediction beyond conventional cardiovascular assessment.
That may require combining several forms of information rather than relying on one test: hypertension history, cumulative occupational exposure, training history, electrocardiography, cardiac structure, rhythm monitoring and perhaps tissue characterisation with magnetic resonance imaging.
Firefighter health policy is already moving in this direction conceptually.
A US Fire Administration cardiovascular-health workgroup has called for a comprehensive strategy to reduce cardiovascular deaths among fire and emergency medical personnel, explicitly identifying better access to screening and stronger research as priorities. The current active NFPA 1580 standard likewise consolidates occupational medical care, fitness and rehabilitation into a broader health framework.
The new study adds a different question to that agenda.
What should screening actually be looking for?
That question matters because firefighters are not simply another occupational cohort with elevated cardiovascular risk. Their work can create an unusual collision between chronic risk and acute physiological demand.
A person with modest underlying pathology may tolerate daily life without difficulty, yet face a very different cardiovascular challenge while carrying equipment, climbing stairs in extreme heat and operating under intense sympathetic activation.
Fitness itself can therefore be misleading.
A firefighter may demonstrate impressive exercise capacity even while harbouring structural myocardial abnormalities that do not become apparent through conventional ischemia-focused assessment.
The policy challenge is to identify that risk without medicalising every physiological adaptation produced by a physically demanding profession.
The evidence is not yet mature enough to rewrite screening standards, and the limitations of the new study are substantial. Only 35% of the investigated deaths had usable autopsy information. Fatality databases can contain misclassification. The study examined people who died rather than prospectively following the entire firefighter workforce, making it vulnerable to selection bias and preventing direct estimates of incidence.
The comparison with the general US population must also remain contextual. An on-duty firefighter fatality and an all-cause death in the general population are fundamentally different denominators.
Those limitations make prospective research essential.
The authors specifically point toward cardiac magnetic resonance tissue characterisation, better measurement of occupational exposures and arrhythmia surveillance as potential components of future studies. Only then can researchers determine whether the hypertrophy seen at autopsy represents preventable pathological remodelling, benign adaptation or some combination of the two.
That work could eventually have consequences beyond firefighters.
Police officers, emergency medical personnel, military populations and other occupations combine high physical demands with acute stress and may face similar challenges when conventional cardiovascular risk models are applied to populations whose exposure patterns are far from conventional.
For firefighters, however, the policy question is already immediate.
Current prevention appropriately asks whether a firefighter has coronary disease, hypertension and conventional cardiovascular risk factors.
The autopsy evidence suggests the next generation of screening may also need to ask what has happened to the heart muscle itself.
Firefighter cardiovascular screening does not need to abandon the coronary arteries. It may need to stop assuming that they are the whole story.
