Taking a blood-thinning drug in addition to aspirin daily after a heart attack significantly reduced the risk of death, follow-up heart attacks and strokes, according to a six-year study of nearly 46,000 patients in China. Researchers found that the drug, clopidogrel, increased overall survival by 9 percent.

"If early clopidogrel therapy was given in hospital to just 1 million of the 10 million patients who have a heart attack every year then it would, on present evidence, prevent about 5,000 deaths and 5,000 nonfatal reinfarctions and strokes," writes Zhengming Chen of the University of Oxford in a report published in the current issue of the Lancet.

Heart attacks, or myocardial infarctions, continue to rise worldwide, especially in developing countries. Despite improving care, doctors in such countries have limited resources to devote to treatment, so inexpensive drugs are a must. Aspirin and clopidogrel fill the bill, though the authors conclude that the benefits are not limited to any particular population.

Clopidogrel works by blocking the ability of platelets--small blood cells--to clot. Despite the fact that the antiplatelet drug usually takes a few days to take effect, the researchers found that the benefits appeared within hours, reducing death by 11 percent compared to a placebo on the first day of treatment.

The drug also had no major side effects (though roughly five out of every 1,000 patients suffered bleeding from the gums or bruises) and did not interfere with other forms of treatment. Clopidogrel had previously been shown to cut deaths, heart attacks and strokes by 20 percent in patients experiencing chest pain. The authors thus advocate considering the drug for nearly all patients suspected of having had an acute heart attack.