Orlando, Fla. ? Adding Plavix to other anticlotting drugs typically given to heart attack patients saves lives and prevents second heart attacks, two huge international studies found.

The strategy is the first big advance in heart attack care in more than a decade, since modern clot-busters were shown to work, specialists said.

This cheap and simple treatment will have a big impact in the nation’s community hospitals, where most Americans get care, they said.

The results of the two studies were presented Wednesday at an American College of Cardiology conference in Orlando. One of the studies also was published online by the New England Journal of Medicine.

The studies looked at heart attacks caused by a large clot that fully or almost completely blocks a major artery — the type that accounts for about a third of the 865,000 heart attacks each year in the United States and the 10 million worldwide.

These patients can be treated with emergency procedures to open the artery or with medications to dissolve the clot until they can be given an angiogram to see whether they need surgery or angioplasty. But arteries reclose about one-fourth of the time in people given medications, doubling their risk of dying before a procedure can be done.

Plavix already is used to prevent clotting, but its safety and effectiveness for treating major heart attacks while they are happening had not been tested until now.

One study, involving about 46,000 heart attack patients in China, found that the risk of death, stroke or another heart attack was 9 percent lower in patients given Plavix along with standard anti-clotting drugs — aspirin, heparin and the clot-busters TPA or streptokinase — than in those who got the standard drugs alone.

The risks of bleeding and other serious side effects were no different.

“The treatment was very effective and very safe,” said Dr. Zhengming Chen of the University of Oxford in England, who led the Chinese study.

Two weeks of Plavix pills cost $50 to $100 per patient. For every million heart attack patients treated this way, 5,000 deaths and another 5,000 major heart problems or strokes would be prevented, Chen said.

The other study was led by Dr. Marc Sabatine of Harvard and the Brigham and Women’s Hospital in Boston and involved 3,491 heart attack patients in Europe given standard drugs with or without Plavix.

The risk of death, another heart attack or artery reclogging was 21.7 percent in those on standard drugs alone but only 15 percent among those given Plavix. This amounted to a 36 percent lower risk for those taking Plavix.