Sudden cardiac death (SCD) can strike both pro and amateur, young and old. It is particularly disturbing when it happens to an athlete and causes us to stop and re-evaluate exercising for health. Fortunately, it is a rare event. Studies on recreational runners indicate approximately one fatality for every one million man (or woman)-hours exercise per year, or roughly 1 death per 10,000 per year . There are no published statistics on SCD in triathletes, but the number is probably very similar.
There are many causes for SCD. Below age 35 the problem is usually a structural abnormality in the heart muscle, valves, or coronary arteries. These conditions are usually congenital and are difficult to detect. Gross abnormalities are identified at birth or in early childhood (e.g.., the child who gets very short of breath and turns blue running across the playground and is then found to have a heart murmur). However, more subtle abnormalities may not cause any symptoms, allow full athletic development and then suddenly cause death during exercise. One famous example is Pete Maravich (sp?) who had a completely successful NBA career, retired, and then fell dead while playing a recreational B-Ball game. He was found to have an anomalous origin of one of his coronary arteries -- an exceptionally rare congenital abnormality that if triggered just right completely shuts off blood flow to the majority of the heart muscle. No physical exam or routine testing would have identified this.
What are the recommendations ? Every athlete should have a thorough physical exam prior to engaging in training. There are a number of conditions that a skilled physician can identify. Depending on the individual circumstances more testing can be done -- resting EKG, stress EKG, echocardiogram. Some of these are not routine tests in a healthy young person, but if there are clues (such as a family member dying of SCD, or a family history of Marfan's syndrome, or a heart murmur detected on exam) further testing should be done. Also it is vitally important that any new or unusual symptoms be thoroughly investigated. Symptoms such as palpitations, chest pain, or black outs during exercise should *not* be ignored.
For athletes over age 35 the usual cause of SCD is coronary artery disease (CAD). The accumulation of atherosclerotic plaques within a coronary artery that eventually can shut off blood flow to heart muscle resulting in a myocardial infarction (MI) or sudden death. CAD is very common worldwide. Exercise protects against the development of CAD, but it does not provide 100% immunity. The risk factors for CAD are smoking, elevated cholesterol, high blood pressure, diabetes, and a family history of CAD.
Exercise has been shown to be a trigger for MI and SCD, but *regular* exercise protects against this. Sedentary individuals who suddenly engage in vigorous exercise are at particular risk for SCD and MI. All athletes over 35 should have a complete physical, blood cholesterol, and many authorities recommend a resting EKG. Some recommend a screening exercise stress test. High risk groups and others with risk factors for coronary artery disease should definitely have more testing, and the exercise program closely monitored.To re-iterate, all symptoms of chest pain, palpitations, black-outs, etc... should be taken seriously. Several studies have documented that many athletes over age 35 experience warning signs that they ignored prior to their fatal event.
Exercise is healthy, if done regularly. *Regular* exercise slows the development of CAD, and lowers your risk of SCD and MI.
So train smart, get a thorough physical exam and discuss exercise with your doctor, pay attention to warning signs from your body, and recognize the risk factors for CAD. Good health to all.