Sudden-cardiac death is the leading cause of on-duty fatalities. In fact, firefighters are three times more likely to suffer a fatal heart attack than is general population. The reasons are unclear: It may be related to dehydration, exertion, stress, shift work, micro-particulates, poor diet or some combination of these factors. But what is clear is that every effort must be made to identify and deal with cardiac disease in firefighters.
Currently there is no national standard for cardiac testing in firefighters. Some departments perform annual maximal or sub-maximal stress testing protocols. These types of tests are done either on the treadmill or a bicycle, have continuous EKG monitoring and are interpreted by a physician. There are three problems with this approach.
- False Negatives: The basic cardiac stress test that is done without echocardiography or nuclear scanning is a fair test for the detection of advanced heart disease. In an individual with risk factors and symptoms such as chest pain a standard treadmill stress test will catch about 70% of the individuals with significant heart disease. Restated this means that a standard stress test will be wrong 3 out of every ten times. Missing 3 out of every 10 people with significant coronary blockage is not very reassuring.
- False Positives: Stress testing all firefighters without cardiac symptoms makes the risk of false positive test results go way up, likely as high as 50%. The test interprets that the firefighter has disease when they actually don’t. False positives lead to time away from work, expensive medical bills and unnecessary and potentially risky further testing like cardiac catheterization. Cardiologists tell us that stress testing in firefighters will result in one half of the positive tests being false alarms. Half of the positive tests are wrong.
- False Sense of Security: Often firefighters rely on the testing results from a negative stress test and feel that they are clear of heart disease. Stress testing is designed to detect blockages in the coronary arteries that are causing a defect in heart function. These blockages generally have to occlude 80% or more of a coronary artery before they cause a defect in heart function. What we have learned is that this type of blockage is not what is causing sudden death in firefighters. Rather, it is the blockage that is less than 80% in a coronary artery that ruptures and causes a clot in the artery that is responsible for the majority of sudden cardiac death. We all know stories of firefighters dying of heart attacks after a normal stress test. Stress testing alone fails to detect most heart disease.
Would you keep a ladder truck in your fleet if it started half the time and when it did start the ladder only extended half way? Why do we continue to rely on stress tests to detect heart disease? The answer is that heart disease is such a significant problem in the fire service that we have felt obligated to do something. Having a ladder truck that might work some of the time is a little better than having no ladder truck at all.
We can do better. There have been recent firefighter-specific pilot programs and studies done at St. Joseph’s Hospital in Atlanta that point the way to a better approach to the detection of heart disease in firefighters.
To date St. Joseph’s has screened about 500 firefighters over the age of 40 from three different departments for hidden heart disease. They used CT scanning of the heart to determine a calcium score for the coronary arteries. Calcium buildup in the coronary arteries has been shown to be an accurate marker for plaque formation in the arteries of the heart. The higher the calcium level in the arteries of the heart the more advanced the heart disease.
Their findings have been interesting. They found that roughly 35% of the firefighters tested had significant heart disease. Out of the 35% roughly 2% required intervention such as catheterization or bypass surgery. Most of these cases would have never been found using traditional stress testing methods. The other fascinating part was that many times traditional risk factors such as high blood pressure and cholesterol levels were not predictive of which firefighters would have heart disease.
There are several advantages to this type of testing.
- It is inexpensive. Routinely hospitals or imaging centers are offering CT Calcium Scoring for about $100 dollars. Several departments we have worked with have negotiated to have this fee waived as a public service to the community.
- It does not have to be done every year. Current recommendations are that this test be performed every 5 years on firefighters.
- It offers the opportunity for early intervention and prevention of sudden cardiac death. Instead of waiting for a traditional stress test to turn positive we can identify early heart disease and reverse it through diet, exercise and medication where appropriate.
There is no perfect test and this article would be incomplete without consideration of the negatives of this type of testing. The chief issue with this type of testing is radiation exposure. Each test gives about 8 milliseiverts of radiation. Current occupational recommendations are that radiation exposures be maintained under 50 milliseiverts per year. 8mSV is well below the 50mSV recommendation however it should be a consideration particularly if you have a firefighter that has multiple recent imaging studies.
The other issue with this type of testing is that you need someone you trust to review the results with your firefighters. Without this proper medical supervision the results are prone to misinterpretation and firefighters may be worried unnecessarily. Referrals and counseling need to be done in accordance with current medical guidelines and standards.
Cardiac CT Calcium Scoring provides a better means of detecting hidden heart disease in firefighters than traditional stress testing. We recommend a medically directed program that will help manage the results with appropriate counseling and referral when necessary.
Dr. Gonzalo Fernandez earned his undergraduate degree from Emory University in Atlanta and is a graduate of the Medical College of Georgia. He completed his residency at Floyd Medical Center in Rome, Ga., and has been practicing in North Carolina since 2001. He is the Corporate Consulting Physician for Progress Energy and has extensive experience in hazmat, fire brigade and firefighter exams. He is also a national lecturer of NFPA 1582 related topics. He can be reached at email@example.com.
Dr. Lance Walker completed undergraduate training in Biology at William Jewell College in Liberty, Mo. He received a Doctorate Degree in Osteopathic Medicine from the Oklahoma State University College of Osteopathic Medicine. His residency was completed in Family Medicine at Floyd Medical Center in Rome, Ga. He is the Associate Medical Director for Georgia Power, and also serves as an Aviation Medical Examiner, Certified Independent Medical Examiner and a Certified Medical Review Officer. He can be reached at firstname.lastname@example.org.
Fernandez and Walker are affiliated with SiteMed, is a physician owned occupational medicine company specializing in on-site firefighter exams.