If an army hopeful can just fall dead, what about me?

Dear Doctor,
A few days ago, I read an article in a newspaper about a young army recruit who fainted after a marathon race that was part of the recruitment process. It was reported that he later died. This has caused me a lot of concern, especially since my whole family and I have been preparing to participate in an upcoming charity marathon. If a young, obviously fit, man who was strong enough to try for the army could die from a marathon race, what are the implications for the rest of us?
Baba Kim.

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Dear Baba Kim,

What you are describing is called Sudden Adult Death Syndrome (SADS), Sudden Arrhythmia Death Syndrome or Sudden Cardiac Death in Young People. This is when death that is non-traumatic, non-violent and is unexpected occurs in a young person who was observed to be healthy six hours earlier. It often results from cardiac failure.

In some western literature, SADS has been noted to occur once in every 1,000 members of the population. Locally, no studies have been undertaken. The condition is usually described in those under 35 years of age, and is more common in men than women.

It has been associated with sporting activities, and has been in the news frequently in the last five years as a cause of sudden death in professional athletes. It is important to point out that the sport is not the cause of death.

There are several conditions associated with SADS. These are:

  • Cardiomyopathy (abnormal heart enlargement; there are different kinds)
  • Coronary artery disease (resulting in the more traditional “heart attack”)
  • Vulvular heart disease (problems with the heart valves)
  • Congenital long QT syndrome/ Brugada syndrome (the ion channels in the heart work abnormally)
  • Various congenital heart diseases (some present late)
  • Cardiac arrhythmias (abnormalities of electrical impulse conduction in the heart, eg Wolf Parkinson White Syndrome)
  • Myocarditis (inflammation of the heart muscle cells)

Hypertrophic Cardiomyopathy (HCM) is one of the most common causes of SADS. Abnormally enlarged heart muscles characterise this condition. HCM is most commonly a result of genetic mutation. Unlike in body-building, where larger muscles may mean greater strength, when the heart muscles are abnormally large, the heart malfunctions when exposed to stress, such as exercise.

Electrical activity

Each heart muscle cell has the potential to conduct electrical activity, and the conducted electrical activity directs how the heart works. In HCM, there is disruption of normal conduction in the muscle cells (arrhythmia).

When a sudden death occurs, such as you describe, it is often necessary to perform a post-mortem exam. It is then that the pathologist will discover that the person had an abnormally large heart. HCM is almost always a quiet condition; therefore it is usually noted after death.

HCM is not common (less than one per cent in the general population), therefore it is not something you should worry about. In families where there has been a recorded sudden death in a young member, the rest of the family should have counselling and, possibly, testing.

The testing could be simply an ultrasound of the heart (echocardiogram) or genetic testing. When HCM is noted before sudden death, specific treatment can be initiated that will reduce the likelihood of sudden heart failure. In some western countries, athletic associations are requiring mandatory testing of all young professional athletes to rule out undiagnosed HCM.

Strenuous activity

HCM can present itself with symptoms, especially in older individuals who have had progressive features of heart failure, and in whom there is no frequent exposure to high levels of strenuous activity, such as in athletes. Your doctor will certainly recognise any of these symptoms.

The other medical conditions listed are also associated with SADS, but are not common. Of note is the association with cocaine use. In the developed world, it has become a major public health concern due to the number of young people dying of sudden heart failure associated with cocaine use. Most of the usage is recreational, and death can result from quantities that do not qualify for overdose levels.

Therefore, Baba Kim, it should be safe for you and your family to participate in the marathon, especially if you have been training well and you limit yourselves to what you’re realistically capable of achieving. Keeping fit will ensure you avoid many more frequent conditions than HCM. Keep it up!

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