Testing can determine the risk of coronary artery disease in runners

By Diamond Fernandes

Running is a great aerobic endurance exercise and has many heart-healthy benefits. However, there is concern that running can turn into extreme exercise, such as marathon running or triathlons. What is extreme? That depends on your fitness level and the amount of training you are doing before getting into running. Some people are natural runners, while some people need to get fit before running. Either way, it is important to know your risk because no one is immune to heart disease.

Heart disease continues to be the leading cause of death of men and women, yet it is also the number one preventable disease. Just because you may appear, or are, physically fit, it does not make you immune to coronary artery disease (CAD).

Regular physical activity is good for all your modifiable risk factors to coronary artery disease. You can reduce or control your blood pressure, improve your HDL (good) cholesterol, lower your LDL and triglycerides (bad) cholesterols, control your weight, improve your glucose metabolism – especially if you are diabetic — and it’s great at controlling the effects of stress. The literature in support of those who maintain a good exercise regimen to lighten their burden for CAD is compelling.

It is likely you can run and have nothing happen to you. Though, occasionally, some forms of heart disease only manifest themselves during endurance activity. Many marathons and triathlons provide defibrillators along the course, but wouldn’t you rather avoid the prospect of needing an electrical kick-start to save your life? Early detection of subclinical disease should clearly be the first-line approach to prevent heart attacks and strokes in athletes, including runners and marathoners.

But coronary artery disease can stay hidden, or be subclinical, meaning disease stays below the surface of clinical detection. Clinical CAD has signs and symptoms that can be recognized. Atherosclerosis is plaque build up inside your arteries – a form of hardening of your arteries. This can lead to a heart attack or stroke. It can lead also lead to angina, which can manifest as chest discomfort. Angina is a condition where your heart is not getting enough oxygen due to atherosclerosis. 

Coronary artery disease is the main cause of exercise-associated death in persons beyond age 35. Research shows, in those older than 35, CAD is the most frequent cause of heart attacks and strokes (80%), followed by valvular heart disease (16%) and hypertrophic cardiomyopathy (3%).

Hypertrophic cardiomyopathy is a genetic condition in which the heart is enlarged, making the it vulnerable to fatal heart rhythms. Hospitals and clinics will commonly use cardiac troponins (a blood test) in combination with an electrocardiogram to diagnose heightened conditions such as a heart attack or coronary artery disease. Research has shown that cardiac troponins increase with the damage that can accrue running long distances, such as marathons.

Running continuously for prolonged periods of time stresses your heart, and some runners have been shown to have minor reduced heart function after a marathon.

None of this is to suggest you should stop running. It is important to know what your heart can withstand. If you are starting a running program, starting to run competitively for longer distances, or are pushing yourself, then it is good to have the peace of mind of knowing your cardiac fitness.

Runners, especially those with a family history of heart disease and other coronary risk factors, should seek medical advice immediately if they develop symptoms suggestive of heart disease.

This could be chest pain, radiating pain to the jaw, neck, shoulder or arms, or even indigestion.

Physicians should not assume physically fit runners cannot have serious cardiac disease. When you visit your doctor, more than likely they will not perform tests indiscriminately.

They may perform a Framingham risk score, which consists of going over your risk factors to heart disease (cholesterol profile, smoking, blood pressure, and age). The concern is it may underestimate your risk for heart disease.

Typical coronary artery disease diagnostic tests on physically fit persons are an echocardiogram and a stress test. These are non-invasive diagnostic tests with no radiation.

An echocardiogram is an ultrasound of the heart looking at its structure and function.

A stress test is designed to see how your heart responds to exercise. It is a great test to do, however the concern is if you are physically fit your test may be terminated too soon. It is important to get a true maximum as standard clinical exercise tests may not always help to identify coronary artery disease in long-
distance runners.

Angiograms are the gold standard test for CAD. The chances of getting an angiogram are slim, unless you are experiencing a heart attack, stroke, or you have other symptoms. You really don’t want to undergo this type of testing as a preventative measure as there is a fair amount of radiation exposure.

Carotid IMT testing looks inside the arteries in your neck (carotid) at the intima media lining thickness. A thicker lining is a good predictor of CAD risk. This is a safe, quick, non-invasive, accurate, and radiation-free screening. If this presents at risk then it would be a good idea to proceed to further diagnostic cardiac investigations.

It is important to know your own risk and not depend exclusively on your doctors and healthcare team. Don’t assume if you are physically fit that you are immune to heart disease. Education, awareness, and knowledge are powerful assets to keep you healthy and on track in your running life.

Cardiac exercise physiologist Diamond Fernandes is the founder and director of Heart Fit Clinic in Calgary.

March/April 2011 Issue