Bypass surgery is still the most effective treatment for most problems involving heart artery clogging, a study comparing Boston Scientific Corp.'s Taxus Express drug-coated stents with the intrusive bypass has found. However, stents proved safe even in patients with severe artery problems.

It appears that drug-coated stents will soon be used as a primary choice for patients who do not qualify for bypass surgery or do not want to do it from other reasons. However, bypass seems for the moment the best option for those patients able to support it.

Bypass surgery treats arterial clogging by bypassing the clot with a newly created blood pathway, usually a blood vessel extracted from another part of the body. If successful, the surgery effectively restores blood flow to levels similar to those before the blockage. Stents attempt to repair the clot by expanding the artery through angioplasty and then propping it open with a special drug-coated mesh. However, the foreign object's presence in the blood vessel is not without complications.

In mid-August, a report found that angioplasty or stent surgery may provide more short-term relief for some patients that suffer from chronic chest pain. The advantages for angioplasty at relieving pain in these cases tend to fade over the years and vanish after three years.

European studies found that newer stents combined with drugs to reduce scarring in arteries might raise the risk of deadly clots. Dutch researchers said in March that patients who had an additional stent implanted as emergency treatment for their stent thrombosis were at an increased risk for cardiac death or recurrent thrombosis.

Heart stents are tiny metal devices that are inserted into the arteries to keep them from clogging up with damaging plaque which can lead to heart attack. Companies manufacturing such devices in the U.S. include Boston Scientific Corp., Johnson & Johnson and Medtronic Inc. About 1 million angioplasties are done in the United States each year.