IT IS, literally, sudden death, and a new National Heart Centre survey finds about one to two Singaporeans below 60 fall victim to it every day.

They die from sudden cardiac arrest, a condition where the heart stops functioning without any external hint of anything being wrong at all.

Such an attack occurs when heart abnormalities - such as a blocked artery - cause the organ to beat very fast. This hinders blood flow, starves the brain of oxygen and kills in five to 10 minutes.

Potential victims are also the ones who are more likely to get any kinds of heart problems because they are obese, have high cholesterol levels, hypertension or diabetes.

Regular heart check-ups and immediate medical attention can prevent about 50 to 60 per cent of these deaths, doctors say.

Unlike a heart attack - which is usually preceded by symptoms such as chest pains or sweating - cardiac arrest has no external symptoms.

A senior consultant at the National Heart Centre, Dr Teo Wee Siong, said yesterday it kills about 1,000 Singaporeans every year, about half of whom are below 60 years old.

In his study of 229 deaths from cardiac arrest last year, he discovered that in about 80 per cent of the cases, the condition was triggered by blocked arteries. The best way to stem cardiac arrest is to give the heart a high-energy shock with a set of instruments known as defibrillators.

But as these devices are usually found in hospitals and ambulances, 'if you collapse elsewhere, there is only a 4-per-cent chance you will survive', said Dr Teo. So the only realistic treatment is early detection through check-ups.

That is how civil servant S. M. Tan, 43, found out he was in danger of having one. He was fitted with an internal defibrillator, which kicked in and saved his life.