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Measuring certain proteins through a simple blood test may make heart disease easier to detect and a lot less deadly, according to a study published online Sunday in the New England Journal of Medicine.

People with healthy LDL-cholesterol levels but elevated levels of high-sensitivity C-reactive proteins experienced a nearly 50-per-cent reduction in the risk of heart attack, stroke, and cardiovascular death with a daily dose of a cholesterol-lowering statin drug, the study found.

The reduction in heart-disease risk among people who appear healthy and lack risk factors such as elevated cholesterol – which describes about half of those who experience heart disease – is such a significant finding that the drug trial was cut short in order to publish the results sooner.

The nearly 18,000 patients followed in the study had normal cholesterol levels and slightly elevated levels of C-reactive proteins – markers of inflammation that are known indicators of atherosclerosis, or blockage of the arteries.

The researchers suspected statin medications such as rosuvastatin would lower the risk of cardiovascular events in such patients, whose LDL-cholesterol levels were below 3.36 millimoles per litre, but were surprised by how well they worked.

“We expected that we would have a robust reduction in heart disease but not to the level that we observed, which means that C-reactive proteins did allow us to target a high-risk population,” said Dr. Jacques Genest, director of McGill University Health Unit's cardiology division.

C-reactive proteins occur in concentrations of tens of thousands of milligrams per litre in the blood of a person who becomes ill. Mildly elevated levels of two to 10 milligrams per litre can indicate atherosclerosis.

Dr. Genest, the study's lead Canadian investigator, and his colleagues found that daily oral doses of 20 milligrams of rosuvastatin led to a 54-per-cent reduction in heart attack, a 48-per-cent reduction in stroke and a 46-per-cent reduction in the need for angioplasty or bypass surgery.

Patients in the study who were given rosuvastatin rather than a placebo showed a 20-per-cent reduction in mortality.

AstraZeneca, a pharmaceutical company that markets rosuvastatin under the brand name Crestor, funded the study.

“The data show that they are protected once they are treated [with statins] but this population previously would not have been considered at all, because there's just no marker to show that their cholesterol is high,” said Dr. Peter Liu, scientific director of the Institute of Circulatory and Respiratory Health at the Canadian Institutes of Health Research. “This may help to detect additional people who may be at risk and now we can actually protect them.”

The “big surprise,” according to Dr. Liu, is that the coronary-event-reducing power of statin medications was even greater among low-cholesterol, high-C-reactive protein individuals than it is among people with high cholesterol.

The trial had been scheduled to continue for four years, but was stopped by the data and safety monitoring board after less than two years because of the life-saving significance of the results.

Health benefits were also exhibited among women and minorities, groups for which clear heart-disease risk factors and treatments have been slow to emerge.

Health-care professionals expect that these findings will change the way doctors screen for heart disease and that patients who previously slipped under the risk-factor radar will now be better protected.

“It's a very important study from that point of view because one of the biggest problems for physicians, particularly primary-care physicians, is trying to decide, ‘Should this 60-year-old be on cholesterol-lowering medication?' ” said Dr. Ruth McPherson, director of the Lipid Clinic at the Ottawa Heart Institute.

This decision is not commonly informed by levels of C-reactive proteins, which can be measured through a simple blood test, she said, but in light of these findings, that is likely to change.

Statin medications such as rosuvastatin lower cholesterol by inhibiting an enzyme important to cholesterol synthesis, but are also known to prevent blood clots and curb inflammation.