Community hospitals that lack highly sophisticated labs for heart procedures can provide top-notch care to heart attack victims simply by giving them clot-dissolving drugs and other medicines, a new study suggests.

The long-awaited report shows that heart attack victims don't benefit from immediately receiving balloon angioplasty, an expensive procedure that opens up clogged arteries in their hearts.Heart attacks occur when clots plug up already narrowed blood vessels that feed the heart. Unless the clot is broken up quickly, part of the heart muscle is starved of oxygen and dies.

Two relatively new drugs, tissue plasminogen activator, or TPA, and streptokinase, can melt these clots and save the heart if given quickly after the attack begins.

Many experts had reasoned that people's chances woud be even better if they then received angioplasty within a day or two of their heart attacks. In this procedure, a balloon is threaded into the narrow heart artery and temporarily inflated, squeezing back the fatty buildups that clog it.

In the latest study, doctors found that people who got TPA, aspirin and a blood-thinning drug called heparin did just as well as those who also received angioplasty.

In both groups, 93 percent were still alive after one year, an exceptionally high proportion.

"There does not appear to be any additional benefit from angioplasty," said the study's director, Dr. Eugene Braunwald of Brigham and Women's Hospital in Boston.

Heart attacks are the nation's biggest killer, accounting for 540,000 deaths annually.