It is rare for young people to die suddenly, said Dr Peter Yan, a cardiologist of Peter Yan Cardiology Clinic.
If it does occur, it is usually among people who do a lot of strenuous physical activities or play competitive sports.
"When a sudden death occurs, it is likely a heart problem rather than a lung problem," he added.
Dr Paul Chiam, a cardiologist at Mount Elizabeth Hospital, agreed.
Non-heart-related causes like a massive stroke or a massive pulmonary embolism, which occurs when there is a blood clot in the major lung artery, are also possible but less likely, he said.
Both cardiologists said that sudden cardiac arrests strike people from different age groups differently.
Said Dr Yan: "Coronary heart disease - clogged arteries - usually hits those above 35 years old, while the younger ones hit by a sudden cardiac arrest usually have congenital abnormalities."
One common abnormality is hypertrophic cardiomyopathy, in which the heart muscles grow very thick.
"Instead of contracting, the heart quivers and cannot pump blood around the body and to the brain," Dr Yan said.
Another cause is channelopathy, the imbalance of electrolytes within the heart muscle cells.
"These electrolytes are essential for the heart muscle to function properly. An imbalance could cause the heart to stop," he said.
Myocarditis, the inflammation of the heart muscle due to a viral infection, is another cause which occurs when a child's immunity drops.
The risk of sudden death due to coronary heart disease can be reduced by controlling cardiac risk factors like diabetes and hypertension, said Dr Chiam.
As for congenital abnormalities, they may be detected only through tests such as an electrocardiography, he added.
Dr Yan said the next best alternative is to make sure that the nation is well trained in giving cardiopulmonary resuscitation (CPR).
"CPR will buy you some time. But still the definitive treatment is to use the AED (automated external defibrillator).
"If you can't get a diagnosis made or find an AED within 10 minutes, your chance of survival deteriorates," he said.
This article was first published on August 15, 2014.
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