MONDAY, Oct. 4, 2004 (HealthDayNews) -- If you have a brother or sister who had a heart attack at an early age, start paying attention to your own arteries because you're at increased risk for heart trouble, a new study finds.
It has long been accepted that a family history of heart disease is a sign of potential problems, said Dr. Roger S. Blumenthal, director of the Johns Hopkins University Ciccarone Preventive Cardiology Center. But the new study he led helps define that risk.
The researchers used an advanced diagnostic technique called electron beam tomography to look for calcium deposits in more than 8,500 people with no apparent symptoms of heart disease. These deposits can eventually grow to block an artery.
As expected, the test found that anyone whose father or mother had had a heart attack was almost twice as likely to have such deposits as someone whose parents had not had such an event. But it also found that anyone with a brother or sister who'd had an early heart attack was three times as likely to have such deposits.
"Our data strongly support the idea that the use of family history in assessing risk is important," Blumenthal said.
The study appears in the Oct. 5 issue of Circulation.
The researchers chose to look for calcium deposits because they provide an early warning sign of heart trouble, Blumenthal said. "Other studies will have to look at end points such as death," he added.
Even before those studies are done, Blumenthal thinks the evidence is strong enough for family history to be added to the four major risk factors for heart disease that were identified by the landmark Framingham Heart Study. Those risk factors are elevated levels of cholesterol and blood pressure, as well as age and cigarette smoking.
It was the Framingham study that identified a doubled cardiac risk for someone with a parent who had had a major heart problem, Blumenthal said.
"Now they are analyzing data on whether having a brother or sister with a cardiac event indicates an increased risk," Blumenthal said. "My suspicion, based on our data, is that having such a brother or sister will have greater prognostic power."
He suggests that anyone with a sibling with heart trouble have a diagnostic test beyond the standard measures of risk. One test that Blumenthal recommends is for blood levels of C-reactive protein, a marker of inflammation that has been linked in many studies to increased heart disease risk.
The American Heart Association (AHA) does not recommend the electron beam tomography test used in the Hopkins study because "there is, as yet, no data demonstrating that actual outcomes are improved in patients who have the test and have an intervention based on the finding," an AHA statement said.
Whatever extra tests might be done, Dr. Robert O. Bonow, a professor of medicine at Northwestern University and a spokesman for the American Heart Association, said, "It is reasonable to recommend that all treatable risk factors should be identified and treated very aggressively" when a young brother or sister has a heart attack.
"What might be a satisfactory level of LDL [bad] cholesterol for an average person might be high for such a person," Bonow said. "The same goes for blood pressure. And those people above all should not be smoking. You can't control your genes, but you can control your smoking habits."
The American Heart Association has more on the risk factors for heart disease.