The last Standard Chartered Marathon Singapore had 65,000 participants, more than double the figure five years ago. This highlights Singaporeans' growing passion for endurance sports events. For all the hype and excitement generated by such events, we should realise that danger, and even death, lurk around the corner. And when deaths do occur, everyone is shocked. Why do these young individuals, paragons of fitness and good health, drop dead after physical exertion? The cause - sudden cardiac death. Statistically, it is rare in young individuals, with the risk being 1.2 to 2.3 in every 100,000 per year for those aged below 35. The most common causes of sudden cardiac death in competitive athletes who are younger than 35 years old differ from those who are older than 35 years old. For those aged above 35 years old, the major cause of sudden cardiac death is coronary artery disease. For the younger athletes, the majority have congenital heart conditions, meaning they were born with the conditions. The most common of such conditions is the thickening of heart muscles and is the cause of three in 10 young athletes who die suddenly. Another condition, in which blood vessels supplying the heart are abnormally positioned and may result in blood supply being cut off in extreme physical exertion, is responsible for one in 10 deaths. Then there is congenital scarring of the right heart muscles, which may lead to life-threatening arrhythmia (abnormal heart rhythm) during exercise. Disorder in the balance of electrolytes (sodium, chloride and potassium, which are vital for cell function) can also result in electrical instability, which leads to lethal arrhythmia. The question: Are these deaths preventable? Certainly, medical screening can pick up such underlying heart conditions. In cardiovascular screening, doctors first identify those at a higher risk of such conditions, such as those with a family history of heart attacks, by using a set of questionnaires modified from the American Heart Association's. These screening tests can be divided into basic and more sophisticated ones. The basic ones include electrocardiography (ECG), treadmill stress test, echocardiogram and 24-hour Holter monitoring, which uses a machine that continuously records the heart's rhythm. The more sophisticated ones include scanning the heart by magnetic resonance imaging (MRI) and or computed tomography (CT). We always start off with the basic ones and only when we pick up something abnormal do we proceed to more sophisticated tests. While such tests are useful, they are not without limitations. Some heart conditions cannot be picked up by ECG and need further sophisticated cardiac evaluation. Nonetheless, if these medical tests can pick up these conditions, doesn't it make sense to make it compulsory for endurance sports participants and even national servicemen (NSFs) to be screened beforehand? In Italy, the rate of sudden cardiac death among athletes decreased by almost 10-fold after ECG screening was mandated in 1982. It fell from 3.6 per 100,000 athlete-years (the product of the number of athletes and the length of time they were in the study) in 1979 to 0.4 per 100,000 athlete-years in 2004. This underscores the usefulness of ECG in preventing sudden cardiac deaths. However, to what extent are we willing to prevent such deaths through routine pre-participation screening and to what extent can screening prevent sudden deaths? This is highly debatable. Many times, we tend to focus on the cost-effectiveness of such tests. Those opposed to screening cite the huge price tag of $3 million to screen every 10,000 NS recruits to prevent a relatively tiny risk of sudden cardiac death. (3,000,000/10,000=SGD 300 per NS recruits)
Logistically, it may also pose a challenge. But the flip side is, how much value do we place on a human life? I have seen anxious parents take their sons for full cardiovascular screening before the pre-enlistment medical check-up to see whether any underlying heart conditions can be picked up. After all, statistics here have shown that one in 14 NSFs who go through pre-enlistment screening are found to have abnormal ECGs and one in 250 may have moderate to severe heart problems and are eventually exempted from combat duty. In my experience, two in three parents whose sons have no abnormalities detected in the non-invasive round of screening tests are reassured. Ultimately, it is up to the individual and the family to decide whether to go ahead with such screening. If they are genuinely concerned and can afford it, nothing should stop them from having the tests done at an established medical centre. While sudden cardiac deaths are rare among the young, we need to bear in mind that such deaths can be better prevented by putting individuals through tests. The grief of loved ones grappling with the sudden deaths of endurance sports participants and NSFs cannot be described by words, much less have a dollar value tagged to it.
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Dr Peter Yan is the medical director of the Parkway Heart and Vascular Centre. He has more than 30 years experience in treating heart and cardiovascular diseases.
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