Cholesterol-lowering statins are one of the most popular prescription drugs in the United States, with nearly 140 million prescriptions dispensed last year, according to IMS Health, a health market research firm. Numerous clinical trials have shown that lowering LDL cholesterol improves heart health.

Still, the question has remained just how low LDL cholesterol should go; many doctors argue that the standard dose is sufficient while others say the drugs should be used more aggressively. A study published this week in the Journal of the American Medical Association attempted to inform that debate, at least as it applies to people who have had a heart attack before. By pitting different doses of the popular statins Zocor and Lipitor against each other, an international team of researchers found that the more aggressive treatment lowered risk of a repeat heart attack but did not change the risk of death from a heart-related problem.

"The big message for patients is, 'Lower your cholesterol a lot,' " says Brigham and Women's Hospital cardiologist Christopher Cannon, who wrote an editorial about the study in the same issue of the journal. He points out that though death rates were not affected by the aggressive treatment, nonfatal heart problems were reduced with the higher statin dose. This is the fourth large study, says Cannon, to show a benefit to dramatically lowering cholesterol.

The trial followed nearly 9,000 northern Europeans—mostly men who had previously had a heart attack—for about five years. Half of the participants were given a standard dose of 20 milligrams of Zocor each day; the other half received 80 milligrams of the stronger statin, Lipitor. Though it did not affect death rates, Lipitor reduced the risk of another heart attack by 17 percent. Pfizer, the maker of Lipitor, sponsored the study and analyzed the data.

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