THURSDAY, Nov. 1 (HealthDay News) -- Heart disease or a heart attack can signal raised cardiovascular risks for an individual's brothers or sisters, too, U.S. researchers report.

The risk for siblings is particularly strong among brothers, the Johns Hopkins University team found. For example, if one brother has a heart attack or chest pain from blocked arteries, the other is 20 percent more likely to also have a heart attack.

The risk for sisters is less, but there also appears to be about a 7 percent increased risk for them, according to the report in the Nov. 1 issue of the American Journal of Cardiology.

"The thing that really struck us was the large number of people who had heart attack or near-heart attacks because of clogged arteries," said lead researcher Dr. Dhananjay Vaidya, an assistant professor of medicine.

In 2005, these researchers found that siblings with a family history of heart disease who were obese or overweight had a 60 percent increased risk of having a heart attack before age 60.

In this study, Vaidya's team collected data on 800 brothers and sisters aged 30 to 60 who participated in the Sibling and Family Heart Study.

Vaidya said his group expected about 10 percent of the brothers to suffer a heart attack, as occurs in the general population. However, "we found instead of 10 percent of the brothers getting heart attacks, 20 percent of the brothers got heart attacks over 10 years of following them," he said.

Among sisters, the researchers expected about 6 percent of them to have heart attacks, but 7 percent had heart attacks, Vaidya said. "That might be because women tend to get heart attacks at a later age than men," he said.

If a man has a sibling who had had a heart attack relatively early in life, then they should be considered at increased risk for a heart attack, Vaidya said.

He believes genetics lies at the bottom of this increased risk, but other factors may be at work as well.

"Siblings are alike genetically and in many other ways," Vaidya said. "Part of the challenge in the future would be trying to see what part of the risk comes from genetics and what part of it comes from living a life that is so like each other," he said.

For now, Vaidya advised that siblings at risk for heart attack modify their risk factors by not smoking, keeping their weight down, exercising and watching their cholesterol.

One expert agreed that understanding your risk is key to minimizing it.

"Cardiovascular disease is preventable, and thus identifying individuals at risk is important and actionable," said Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles.

"Individuals with a family history for premature cardiovascular disease should be carefully evaluated and take action to modify their cardiovascular risk including achieving healthy blood pressure, lipid levels and weight, as well as not smoking and exercising," Fonarow added.

Another expert applauded the study.

"This is a very important paper that shows that a family history of premature coronary heart disease has important prognostic value," said Dr. Roger S. Blumenthal, a professor of medicine and director of The Johns Hopkins Ciccarone Center for the Prevention of Heart Disease. He was not involved in the study.

Unfortunately, this variable is not included in the standard Framingham Risk Equation, which doctors often use to determine which adults should get aspirin or cholesterol-lowering therapy, Blumenthal said.

"Health care providers need to take family history into account when they are trying to decide which patient should go on prophylactic aspirin or statin therapy," he said.

"Clearly more events occur among family members of persons with premature heart disease than would be predicted by the Framingham risk score," Blumenthal noted. "The excess risk in these families cannot be attributed to traditional risk factors."

More information

For more on heart attacks, visit the American Heart Association.

SOURCES: Dhananjay Vaidya, M.B.B.S., Ph.D., assistant professor, medicine, Johns Hopkins University, Baltimore; Gregg C. Fonarow, M.D., professor, cardiology, University of California, Los Angeles; Roger S. Blumenthal, M.D., professor, medicine, director, The Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Baltimore; Nov. 1, 2007, American Journal of Cardiology

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