The study, by researchers from Northwestern University and the Framingham Heart Study, showed a doubling of cardiovascular risk in men and a 70 percent increased risk in women who had at least one parent with early onset cardiovascular disease (younger than 55 in the father and younger than 65 in the mother). These increased risks were found after accounting for other risk factors, such as high cholesterol, hypertension, obesity, cigarette smoking and diabetes.
When both parents had early-onset cardiovascular disease, children were at even greater risk for a heart attack or stroke.
"Our results shed important light on the true magnitude of the association between offspring and parental cardiovascular disease," said Donald M. Lloyd-Jones, M.D., first author on the study.
Lloyd-Jones is assistant professor of preventive medicine and assistant professor of medicine, division of cardiology, at Northwestern University Feinberg School of Medicine.
The parent group in the Framingham study has been followed up for over 50 years, and their children for more than 30 years. This provided the investigators with a unique opportunity to examine the true relationship of parental and offspring cardiovascular disease, confirmed by a physician panel of experts, without the potential bias of often-inaccurate self-reporting that has limited similar studies.
The researchers studied over 2,300 offspring participants, average age 44 years, in the Framingham Heart Study. Of these, 164 men and 79 women had a heart attack or stroke during follow-up.
In addition to the other study findings, the data showed that if children had very favorable personal risk factor levels, cardiovascular disease in parents did not increase the children's risk. If children had very unfavorable levels of risk factors, the absence of cardiovascular disease in parents did not lower their risk.
Importantly, the occurrence of parents' cardiovascular disease made the most difference in predicting risk for children with intermediate levels of risk factors, for whom decisions about treatment are often difficult. A cardiovascular disease event in parents was a strong predictor of risk in persons with intermediate levels of total cholesterol and intermediate levels of blood pressure, Lloyd-Jones said.
These are levels of cholesterol and blood pressure at which treatment guidelines suggest lifestyle modification and/or drug treatment to lower cholesterol or blood pressure.
"Patients and their physicians ought to be concerned if there is a bona fide parental history of cardiovascular disease, even if there are also just borderline elevations of other risk factors such as cholesterol and blood pressure," Lloyd-Jones said.
Some of the familiar occurrence of cardiovascular disease may be due to risk factors, such as high blood pressure and diabetes, which run in families. However, the fact that premature cardiovascular disease in parents increased a child's risk even after accounting for these risk factors suggests that as yet unidentified genetic factors also play a role, according to study co-author Christopher O'Donnell, M.D., of the National Heart, Lung, and Blood Institute.
This study supports ongoing research to identify important genes that lead to susceptibility to heart attack, strokes and other cardiovascular diseases," the researchers said.
Lloyd-Jones and O'Donnell's co-researchers on the study were Byung-Ho Nam, Ralph B. D'Agostino, Sr., Daniel Levy, M.D., Joanne M. Murabito, M.D., Thomas J. Wang, M.D., and Peter W.F. Wilson, M.D., of the National Heart, Lung, and Blood Institute's Framingham Heart Study.