1,000 cases of sudden cardiac death in Singapore each year — that's equivalent to three cases a day

About 1,000 cases of sudden cardiac death occur among Singaporeans every year.

Half of these deaths occur in people under 60, of which more than 90 per cent are men with a median age of 47.

The median age of women is slightly higher at 50.

Though it is rare, even the young and fit can be struck by this condition.

They could be athletes who do extreme sports or take part in endurance races, putting their heart under a lot of stress, said Dr Eric Hong.

Or they could be what the cardiologist at EH Heart Specialist calls the "weekend warriors".

"They don't exercise regularly to build up their endurance because of lack of time," he said.

Several studies have also linked competitive sports with sudden cardiac deaths.

A 2016 study done in the US has found that sudden cardiac death is the most common medical cause of death in athletes.

One in 40,000 to 80,000 athletes are affected every year.

In Singapore, a study that looked at 55 cases of exercise-related cardiac arrests over eight years found the mean age to be 50.9 years, with a male predominance of 96.4 per cent.

"We found that exercise-related cardiac arrest causes significant mortality in our community," the study said.

Sudden cardiac death happens when there is an abrupt loss of heart function.

According to the National Heart Centre Singapore, it can be due to a variety of heart conditions.

The most common cause is a sudden onset of abnormal heart rhythm - a fast but chaotic heart rhythm called ventricular fibrillation or tachycardia.

When this happens, the heart beats at 400 to 500 beats per minute, causing the normal rhythmic contractions of the lower chambers of the heart to stop.

Blood and oxygen cannot be pumped to the rest of the body, and the brain is starved of oxygen within seconds.

The person loses consciousness as a result.

This is different from a heart attack, which is due to a blockage or occlusion of the arteries supplying blood to the heart.

This causes a portion of the heart muscle to be damaged, and may or may not lead to sudden cardiac death.

EXTREME STRESS

In those who do endurance races, the body is subjected to extreme stress in the final push.

Sudden cardiac death is most likely to happen in the final 1.6km of a 42km marathon, said Dr Hong.

"It (is) known that the final sprint with sudden cessation has also been associated with greater risk.

"This is when sportsmen and women are exhausted, but with the encouragement of the crowd at the finishing line are pushing beyond their physical limits," he said.

He added that it is twice more likely to occur in triathletes than marathon runners, with the occurrence most common in the swimming leg of the event.

"Health screening can identify certain high-risk groups. And if one is at a high risk of sudden cardiac death, then the doctor would usually suggest that the individual avoid competitive sports," said Dr Hong.