Why do firefighters die of heart attacks

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Third, we found a significantly higher prevalence of cardiovascular risk factors among firefighters dying of on-duty CHD as compared to control firefighters. Conversely, we found that on-duty CHD deaths are unlikely to occur in firefighters without traditional cardiovascular risk factors.

Importantly, major cardiovascular risk factors are detectable at routine examinations and mostly modifiable. Therefore, fitness promotion, medical screening and improved medical management could prevent many of these premature deaths, and should be promoted and provided by fire service authorities.

Firefighters often work hour shifts or provide hour coverage through a variety of arrangements. Therefore, if on-duty CHD events had no relation to work, firefighter deaths should have a circadian pattern similar to the general population in whom cardiovascular events peak between 6 am and noon [ 45 - 48 ]. In stark contrast, we found most on-duty CHD fatalities occurred between noon and midnight.

In agreement, a year study of all U. Although the FEMA study did not hypothesize a reason for this afternoon-evening predominance, the most likely explanation is the higher volume of emergency calls during the latter half of the day. Investigators have hypothesized that the morning excess in cardiovascular events among the general population is due to morning increases in arterial blood pressure, catecholamines, coronary tone, platelet aggregability, blood viscosity and a relative increase in serum cortisol [ 47 ].

Synchronized increases in these factors may also occur during the psychophysiologic arousal of an emergency response.

Our second major result, implicating specific job activities, supports this hypothesis. The most likely explanation for a CHD death risk 60 times that of non-emergency duty is the increased cardiovascular demands of fire suppression [ 13 , 15 - 17 ].

Consistent with the above findings, we found a significantly elevated CHD risk associated with training activities. An episode of heavy exercise, such as a training drill, can be a strong cardiac triggering factor especially among the physically inactive [ 49 , 50 ].

The CHD training deaths in our study primarily involved strenuous drills carried out by victims lacking adequate physical fitness. Most fire departments do not require firefighters to exercise regularly. Womack et al [ 52 ] found that both exercise tolerance and lean body mass were below age-predicted averages in another firefighter cohort.

Furthermore, Roberts, et al [ 53 ] demonstrated elsewhere that even new firefighter recruits were overweight and had low-normal aerobic capacities. Also in agreement with a triggering hypothesis and earlier research documenting increased heart rates in firefighters responding to alarms [ 13 , 14 ], we found a roughly five-fold increase in the relative risk of CHD death during alarm response.

Heart rate and blood pressure increase in response to alarms consistent with fight or flight physiology and remain elevated in unfit firefighters [ 54 ].

In addition, firefighters can be exposed to significant noise from truck sirens during alarm response also increasing blood pressure. Regarding EMS and other non-fire emergencies, we found a smaller, non-significant increase in the risk of CHD death relative to non-emergency duties. We found excess cardiovascular risk factor prevalence among the CHD fatalities in agreement with previous studies regarding: the development of non-fatal CHD in firefighters [ 29 ], fire brigade retirements due to arterial disease [ 55 ], and CHD prediction in the general population [ 43 , 56 ].

Hypertension and hypercholesterolemia were highly prevalent among the CHD decedents in this study. The vast majority of the CHD fatalities in our study had not received a fire department medical examination within two years of the fatal incident, and many had LVH consistent with long-standing hypertension. We have recently shown that hypertension and dyslipidemias are often inadequately treated in firefighters, and that uncontrolled hypertension is associated with a higher risk of adverse changes in employment status [ 51 , 57 , 58 ].

Therefore, we believe that screening alone is insufficient, and fire department medical programs should include incentives to promote more aggressive risk factor reduction. For those who received a medical clearance for return to duty, these evaluations, in retrospect, did not appear to comply fully with the existing NFPA guidelines for firefighters with CHD [ 16 ].

Our results support a mandatory and conservative evaluation of firefighters with arterial occlusive disease as advocated by the NFPA. Most of the victims in this study had not experienced previous symptoms of CHD or did not disclose them. Our results, therefore, should revive the question of stress tests for selected persons in physically demanding occupations. An abnormal exercise test can be an important prognostic indicator especially when combined with other risk factor information. A recent prospective study of over 25, asymptomatic men demonstrated that abnormal exercise tests are highly predictive of subsequent cardiac death, and the association increases for each additional risk factor present [ 60 ].

No clear guidelines exist, however, for stress testing in asymptomatic individuals, even for public safety professionals [ 16 , 61 - 63 ]. Further study is needed to determine the most appropriate and effective strategy. Primary CHD prevention should start with fitness promotion. Comprehensive programs can have beneficial effects on firefighters' risk profiles [ 64 ]. Robust scientific evidence strongly links increased physical fitness to decreases in cardiovascular risk and overall mortality in the general population [ 65 ].

Our study has several potential limitations. We believe this did not affect our findings because the circadian and job activity distributions we found were quite similar to those in the FEMA study including all available U. Thus, our cases were representative in terms of the precipitating circumstances. Although the NIOSH cases included a higher representation of professional firefighters compared to volunteers, we found no significant differences in cardiovascular risk factor prevalence or the frequency of fire service medical examinations between these two groups.

The second potential limitation regarded the estimation of relative risks for specific job-activities using incident and response data from a single fire department for a single fiscal year. While we were aware of this limitation in designing the study, we were unable to find any national data quantifying the proportion of time firefighters spend in various professional duties. In addition, it was impossible to collect such data from each fire department for each fatality.

Because we hypothesized that strenuous emergency activities carry the highest risks of CHD death, we sought an urban fire department to ensure a sufficient level of emergency incidents. Cambridge, Massachusetts has a population of approximately , persons. To the extent that using an urban professional department to estimate the frequency of job activities and emergency responses resulted in overestimates of the extent of fire suppression and other emergency activities for rural and volunteer firefighters, this would have biased our results towards the null hypothesis.

In terms of reliability, the fiscal year incident data we used were quite similar to fiscal years — Our study has several additional limitations regarding the assessment of cardiovascular risk factors.

The less robust than expected relationship of hypercholesterolemia to CHD mortality in our study may be explained by unavailable data for many of the deaths, and the high prevalence of elevated cholesterol among the controls.

Also, we did not have numerical cholesterol data for the CHD death cases. Among Scottish firefighters retiring prematurely due to arterial disease, Ide [ 55 ] found significantly higher cholesterol and triglyceride levels compared to firefighters who completed maximum service. The high prevalence of elevated total cholesterol among firefighters [ 26 , 27 , 29 , 30 ] and its known relationship to CHD strongly support recommendations to include lipid profiles in firefighter medical examinations [ 16 , 67 ].

Second, while we strongly associated diabetes mellitus with CHD death in unadjusted models, the relationship of diabetes to on-duty CHD death lost significance in the multivariate models. Additionally, because many of the decedents were not receiving regular medical examinations, we may have underestimated their prevalence of diabetes.

The unadjusted associations support blood glucose measurement in firefighters and careful cardiovascular evaluations of diabetic firefighters. Third, the comparability of the study groups and the methods of data ascertainment are always potential concerns in case-control studies. We could not use the trauma fatalities we used to compare circadian and job activity to compare cardiovascular risk factors because their NIOSH reports lacked information on personal risk factors. Although we could not completely match the occupational circumstances of the NIOSH CHD cases and the Massachusetts controls used for cardiovascular risk factor prevalence, we believe our choice was reasonable.

The deaths occurred during a comparable period. Although the decedents also included volunteer firefighters, we found no differences in risk factor prevalence between volunteer and professional CHD cases.

Because we used the baseline data from the control Massachusetts firefighters, we minimized the effects of serial examinations on health status. In terms of data ascertainment, information constraints led to an incomplete determination of risk factors among the CHD deaths, and most missing risk factors were coded conservatively as absent negative.

The incomplete determination for the cases, but near universal determination of risk factors in the controls most likely biased our results towards the null hypothesis. Our Massachusetts controls also had several other desirable characteristics. The state does not use physical criteria for selecting hazardous materials team members, and therefore, team participation is not associated with a significant healthy worker effect.

Using Framingham predictions, the average year, predicted CHD risk in these firefighters was essentially identical to that of an average person of the same age from the community [ 68 ]. Third, we have not documented evidence of any adverse health consequences of hazardous materials duty compared to other firefighters [ 69 , 70 ].

The present study provides a firmer basis for developing improved guidelines for determining which CHD events in firefighters are work-related. Our findings support previous suggestions by Guidotti [ 11 ] that events during or within a day after fighting a fire are likely to be work-precipitated. In addition, the onset of symptoms during other work events likely to result in cardiovascular arousal also suggests work-relatedness. If a person is experiencing jaw pain, they must seek urgent medical attention as it may indicate a heart attack.

Learn more. An implantable cardioverter defibrillator monitors heart rhythm and provides an electric shock to correct irregular heart rhythm. We explore how it…. If a doctor suspects that a person has had a heart attack, they will use blood tests and other diagnostic tools to verify the diagnosis. Aspirin can help prevent and manage a heart attack. However, it is not suitable for everyone. Learn more here. Why do firefighters have an increased risk of heart attacks?

Written by Tim Newman on April 4, Share on Pinterest A new study explains the link between firefighting and experiencing cardiovascular events. Kales, M. Author disclosures are on the manuscript. The association makes no representation or guarantee as to their accuracy or reliability. The association receives funding primarily from individuals; foundations and corporations including pharmaceutical, device manufacturers and other companies also make donations and fund specific association programs and events.

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