Sudden Cardiac Death in Young Athletes


English: CPR training with Welch Allyn AED 20

Cardiopulmonary resuscitation training with defibrillator.

Sudden death headlines splash across media when they occur on the sports field.

Sudden collapse and death of a super-fit, young, professional athlete is a tragedy without doubt. Yet these deaths rarely occur, especially considering many young people actively pursue high-intensity sports every day in our modern world? Why do sudden deaths in young athletes occur, and why do athletes seem more at risk?

Two types of sudden cardiac death in young athletes are common. First when they are at rest – or sleep – and the event occurs hours after they have been playing, training or exercising. The second – more common event is during strenuous exercise, but it does not just occur in the young, high-performance athlete.

In soccer, the tragic death of Marc-Vivian Foe – a Cameroon international – died on the field of play in 2003. The recent health scare  – for Bolton midfielder Fabrice Muamba – was also a timely reminder of this silent threat to young sports people who seem extraordinarily healthy athletes.

Why do Sudden Sports Deaths Occur?

Young athletes have greater risk than non-athletes of sudden cardiac death. The exerting extra pressure placed on the heart, through very strenuous exercise is the underlying trigger for sudden death. This is because there is something inherently genetically wrong with those individuals who have a sudden cardiac death at such a young age.

There is an increased risk of a cardiac event in a young person when there is some structural anomaly already present. There are many structural, electrical and acquired cardiac anomalies that can be triggers for a sudden cardiac death. Some of these abnormalities that predispose to sudden death can be identified, and are eminently treatable. So early diagnosis is paramount, especially for someone who is going to adopt a more strenuous exercise regimen in training for sport.

The mandatory screening of young sports people, especially those who follow more stringent exercise regimens, is a preventative approach that has much support. But currently not every future professional sports person undergoes this kind of screen prior to any exercise training regimens that they need to adopt to perform at the top level of their chosen sport.

Prevalence of Sudden Cardiac Death

Up to 2,000 people under 25 die from a sudden cardiac death each year in the US. The risk is three times higher in athletes and sudden cardiac deaths are much more common in males, but to put this in perspective this is a very low number and sudden cardiac deaths are very rare in younger athletes.

It is hard to spot those who are at risk of at an sudden cardiac death before an event. Early symptoms, including dizziness and shortness of breath, are often dismissed by athletes who train very hard and are used to pushing their bodies to the extreme.

There have been evaluations of its prevalence in different athletic population groups. Thr considerable variation depends on the athlete’s gender, the population studied, and the sports in which the athletes participate.

In US athletes, sudden cardiac death occurs at a prevalence of 7 per 1 million of the general population, and it occurs five times higher in males than females.

In Northern Italy – has runs an extensive pre-participation screening programme for sports for 20 years – prevalence is 1.6 per 100,000 in athletes and just under one per 100,000 in non-athletes.

In a population of Rhode Island joggers, the incidence was about 3 per million per year in the younger age group under 35, but 131 per million in the 35-64 age group. Thus debunking the misconception that it occurs mainly in the young athletes.

Is Excessive Exercise Dangerous?

Exercise is not a dangerous activity. But identifing those at risk individuals for whom it may cause an exacerbation in stress will reduce morbidity or mortality.

The health benefits of regular exercise are uncountable. Taking regular exercise benefits people with nearly every kind of illness from mental illnesses – such as depression or dementia – to chronic physical illnesses – such as cancer, diabetes or rheumatoid arthritis.

Performing at extremely competitive levels at a younger age is likely to put considerable pressure on the young person’s body. But how much damage is done to specific individual’s athlete’s heart health over the long-term is hard to measure. If an athlete has a pre-existing heart problem, then the cardiac strain puts them at higher risk of a sudden event when performing competitive sports.

Preventing Sudden Cardiac Death

Sudden cardiac death is triggered by a structural defect in the heart or a problem with the electrical circuitry.

Diagnosing an underlying anomaly that predisposes an individual to risk of a sudden cardiac death ensures that strategies to prevent it can be employed successfully.

Screening all competitive athletes for cardiac anomalies is the ideal preventative strategy for SCD. Once an anomaly is found, then the aim is to start action to prevent it. This can includes choosing various treatments or abstenting from participating in high impact sports. In reality, adopting this approach is not practical because of the economics involved, the limited success rate of screening and the high number of false positives.

The ‘Middle-Aged‘ Risk

Sudden cardiac death while exercising is much more common in middle age. And these older individuals usually die from pre-existing cardiovafscular disease. Many cases go unreported as the cardiac event is triggered by the exercise but it is not often implicated as a cause.

As we age the risk of having a cardiovascular event that leads to a sudden cardiac death while exercising increases –  a fact that is not generally appreciated.

The impact of the frequency of exercise was investigated in a prospective 25 year follow up study of 30,000 nurses in the US. The nurses did low levels of exercise of  about 1 hour per week. The frequency of exercise did not impact the risk of sudden cardiac death. For nurses who exercised more than 7 hours a week, they had a 60-70% reduction in the risk.

Also in a US study of 20,000 male physicians – followed up for about 30 years – exercising 2-4 times per week – showde exercise and vigorous activity was clearly a trigger for cardiac death. But rhe more exercise performed the less likely it happened. The relative risk – one hour exercise versus sedentary activity – was less for men exercising more than five time a week than if they exercised less than once a week.

Defibrillation Improves Survival

Identifying those at risk of sudden cardiac death preserves life, so does responding rapidly to a cardiac event. As the minutes pass by, survival drops by about 10% per minute delay in defibrillation. This rate is improved using good quality cardiopulmonary resuscitation. Performing cardiopulmonary resuscitation before defibrillation improves outcomes even if performed up to 15-20 minutes after an event.

In the past, performing resuscitation for cardiac arrest was impeded by a sense of fatalism. Low percentage survival rates (1%) reflected a sense of futility.

However, defibrillation and good community awareness enhance the likelihood of surviving a cardiac arrest.  The chance of finding shockable rhythm has risen from 19-33% over last five years. If you have a cardiac arrest, survival rates are low if no defibrillator is available; but if one is, then it is much higher.

Cardiac event response is enhanced in particular by improving response at sporting venues. Access to an automated external defibrillator should be in less than three minutes with collapse to defibrillation less than 5 minutes. All club members should be familiar with the concept of cardiac arrest and should be targeted to improve cardiac awareness.

The training of first responders and the availability of more community automated external defibrillator is a prerequisite to improving response times to a sudden cardiac event.

Conclusion

Strenous exercise is a risk in athlete with a hidden cardiac abnormality that puts them at increased risk of a sudden cardiac death.

Managing an underlying abnormality is performed using lifestyle modification, pharmacotherapy, and device therapy. Screening prior to participating in sports is the way to avoid these problems. To make this mandatory is very difficult and the danger is that some athletes slip through the net anyway.

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One Response to “Sudden Cardiac Death in Young Athletes”

  1. Great article, covering everything & more I’ve ever read on the topic.

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