Heart attacks and strokes may be cut by roughly 50 percent among patients who receive preventive doses of a cholesterol-lowering drug known as a statin, according to a large medical study involving 18,000 patients in 26 countries. The study conducted by scientists from Birmingham and Women’s Hospital focused on the drug rosuvastatin, sold as Crestor by drug maker AstraZeneca, which funded the research.

For the study, scientists used a test they pioneered, a tool to screen patients for evidence of cardiovascular disease missed by other cholesterol tests. All participants in the study had very good cholesterol levels but elevated levels of a protein that has been linked to heart disease. The benefits were seen in patients with high levels of a protein called CRP, a phase protein produced by the liver and by adipocytes that points to an inflammation in the body and can be a factor in the development of coronary heart disease, a major cause of disability and death. The participants took 20 milligrams of the drug Rosuvastatin, also known as Crestor, or a placebo pill.

At the end of the study (it was supposed to last four years, but the effects were so beneficial that the study was halted after less than two years, the researchers said) people who took Crestor were also almost 50 percent less likely to suffer a stroke, need angioplasty or bypass surgery, and were about 20 percent less likely to die of heart disease.

Healthy people may benefit from statins too, the study shows. “If your high sensitivity CRP (hsCRP) is high, you should be on statin therapy regardless of your cholesterol level. This is an approach we can start using tomorrow,” said Dr. James Willerson, director of the Texas Heart Institute in Houston.

Statins are usually prescribed to reduce heart risk in people with underlying heart conditions by lowering the amount of cholesterol in the blood. The drugs work by blocking the enzyme HMG-CoA-reductase, which is needed by the body to make cholesterol. The most common adverse side effects found to be associated with the use of statins include muscle pain and muscle weakness.

Drug analysts say the results of the study, presented Sunday at a New Orleans meeting of the American Heart Association, may help AstraZeneca to promote Crestor. They estimate Crestors’ yearly sales will reach $6.33 million by 2015, expanding the $34 billion market for all cholesterol-lowering medicine and preventing 50,000 heart complications a year.

The findings of the study, published in the New England Journal of Medicine, will be taken into “strong consideration” by the National Heart, Lung, and Blood Institute as it revises guidelines on preventing and treating heart attack and stroke next year, said Dr. Elizabeth Nabel, the agency's director. The results suggest an additional 6 million men over age 50 and woman over age 60 should take the drugs, doctors said.

Another interesting phenomenon, noticed by Paul Ridker, the lead investigator from Harvard Medical School in Boston was that half of heart attacks and strokes happen among apparently healthy men and women with normal or low levels of cholesterol. Doctors cannot assume their patients are at low risk of heart disease just because their cholesterol level is normal or low.

Besides reducing heart risk, statins were shown to slow down age-related memory loss and dementia as well.

The study, dubbed Jupiter, highlights the importance of prevention and raises the question of whether statins should be used to develop therapies that would offer an effective prevention for heart disease, America’s number one killer.