CHICAGO (AP) – Researchers have identified a genetic variation in some people that appears to reduce their chances of a heart attack or stroke – even in those with high blood pressure, high cholesterol or other risky conditions.

It is unclear how common the variation is, and some experts said it too soon to say whether routine screening for it would be worthwhile. Other gene variants have been linked with an increased risk for heart attacks and premature heart disease.

In patients with heart-endangering conditions including high blood pressure and high cholesterol, those with the newly identified gene variant face up to a 67 percent reduced risk of having a heart attack or stroke, the researchers said.

The study was done on patients in Italy and was published in Wednesday’s Journal of the American Medical Association.

The variant reduces the activity of a gene involved in producing an enzyme called cox-2 that triggers inflammation, and it is much more common in people who have never had heart attacks or strokes, said study leader Dr. Francesco Cipollone of the G. d’Annunzio University of Chieti, Italy.

The study involved 864 patients who had had a heart attack or stroke and a comparison group of 864 patients who had never had either ailment. Similar numbers of people in both groups had conditions that raise the risk of a heart attack or stroke, including high blood pressure, high cholesterol, diabetes, obesity and smoking.

Blood tests showed one form of the gene variant was more than twice as common in the comparison group than in the heart and stroke patients; a less common form was almost six times more prevalent in the comparison group.

Overall, almost half the comparison-group subjects had the variant, compared with less than 20 percent of the heart attack-stroke group.

The variant was especially common in those over 70, suggesting that people with it are more likely to stay healthy as they grow old, the researchers said.

The variant might be more common in Mediterranean areas than in northern Europe and might help explain regional differences in the incidence of heart attacks, the researchers said.

It is unclear how prevalent the variant is in Americans, since none were studied. But the researchers noted that previous research found the variant was relatively uncommon in the United Kingdom.

Doctors not involved in the research said it would be premature to suggest that people with the variant could ignore the usual heart-healthy advice like eating a sensible diet, getting exercise and avoiding smoking.

“Just because you have this doesn’t mean everything else is OK … that you can abuse yourself and not care of yourself,” said Dr. Michael Sloan of Rush University Medical Center in Chicago.

American Heart Association spokesman Dr. Richard Becker noted that people with the variant did not have zero risk, and said it is too soon to say whether they should receive different prevention and treatment advice.

He also said the results are too preliminary to recommend routine testing for the gene variant.

The Cleveland Clinic’s Dr. Eric Topol said the study adds to data linking various genes with heart disease risk and provides important information about the link between cox-2 and artery disease.

The cox-2 enzyme suppressed by the gene variant plays a role in inflammation. Doctors believe inflammation in the bloodstream contributes to the rupture of fatty buildups inside arteries, which can lead to clots that cause heart attacks and strokes.

The cox-2 enzyme also is believed to play a role in arthritis, and it is targeted by the arthritis drugs Celebrex and Vioxx.

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