A new study which questions the value of putting stents into blocked heart arteries has sent some patients scurrying to ask their doctors if they are carrying useless devices in their bodies.

The Courage trial, done in the United States, found that drugs alone were as good in preventing death and heart attacks in patients who had chest pains - called angina - but were otherwise stable.

The trial involved 2,287 patients at 50 centres in the US and Canada. Half of them were treated with a combination of six drugs, including those which reduced chest pain, lowered cholesterol and blood pressure.

The other half had the same drug therapy as well as angioplasty - a procedure which involves threading a catheter along the artery and inflating a tiny balloon in the clogged area to clear it.

Often, a stent is inserted into the artery at the same time to prop it open, so the procedure has also become known as stenting.

After an average of 41/2 years, about 19 per cent of each group had died or had a heart attack: 211 in the angioplasty group, and 202 in the medication group.

The results showed that for stable patients who have not had a heart attack, it is not always necessary to resort to expensive procedures when medication would do.

Of course, someone having a heart attack - 20 to 30 minutes of prolonged chest pain - or who has very severe and unstable symptoms, would need a life-saving angioplasty.

A clot-busting drug reduces the risk of death during a heart attack by 25 per cent. Angioplasty cuts this even further by another 34 per cent.

But the results do not mean stenting is useless for those who have not had a heart attack.

Angioplasty has this advantage over drugs alone - it is much better at reducing the pain of angina. Even if it does not prolong life, it improves the quality of it.

According to consultants at the National Heart Centre (NHC) and National University Hospital (NUH), stable patients with mild symptoms are usually put on medication first. Angioplasty is an option if the pain does not improve in three to six months.

Other patients who are stable, but have abnormal electrocardiogram or stress test results, are asked to undergo an angiogram, a scope of the heart arteries, and may then get an angioplasty.

Dr Ronald Lee, a consultant at NUH's cardiac department, said that he would recommend angioplasty if the clogged vessel supplies blood to a huge amount of heart muscle and patients had chest pain.

The Courage trial found stenting to be more effective than medication - at least at first - in relieving pain. The difference, however, shrank with time. After five years, 74 per cent of the angioplasty group were free of pain, compared with 72 per cent of the medication group.

Said DrTerrance Chua, NHC's head of cardiology: 'We've always known that for a group of patients, angioplasty improves symptoms, but may not prolong life. Still, we should not deny patients symptom relief.'

Each year, about 5,000 people here have stents inserted, often after a heart attack or severe chest pains.

At the heart centre, about half of patients suspected to have narrowed arteries get an angiogram as their symptoms are severe, Dr Chua estimated. Of these, about half eventually undergo angioplasty.

About 20 per cent of NUH patients who get stents are those with stable chest pains, estimated Dr Lee. He said: 'Even though stenting might not reduce the risk of heart attack or death in certain situations, it helps to reduce chest pain promptly and improve the patient's quality of life.'