Genetics may play more of a role in heart attacks than in strokes, a new British study suggests.
"A family history of heart attack appears to be a stronger risk factor for heart attack than a family history of stroke is for stroke," said study author Amitava Banerjee, a clinical lecturer in cardiovascular medicine at the University of Birmingham in England.
The findings should alter the way doctors predict a patient's risk of heart attack and stroke based on family history, the researchers said. And, "genes and genome-wide association studies may not be critical to the field of stroke research," Banerjee added.
Both stroke and heart attack are leading killers of adults in the United States.
For their report, published in Circulation: Cardiovascular Genetics, Banerjee's team collected data from the Oxford Vascular Study on 906 people who had heart attacks and 1,015 stroke survivors.
What the study found
Among those with heart disease, 30% had a parent with a heart attack and 21% had a sibling with a heart attack, the researchers found.
Seven percent had two or more siblings who suffered heart attacks, and 5% reported both parents had had heart attacks.
On the other hand, 21% of those who suffered a stroke or transient ischemic attack, considered a minor stroke, had at least one parent with a stroke, and 8% had a brother or sister with a stroke.
Two percent of the stroke survivors had two parents with strokes, while 14 % had at least two siblings with a stroke, the researchers found.
When two parents had suffered a heart attack, the risk of heart attack increased six times. If one parent suffered a heart attack, the risk was 1.5 times greater for their offspring.
Stroke risk did not change substantially based on parental stroke history, the authors said.
Heart attacks and strokes in families
The researchers reported that the risk of siblings developing heart problems was similar among those with heart attack or stroke.
"Risk prediction models using family history currently lump a patient's family history of stroke and heart attack together," Banerjee said. "We probably should model family history of stroke and heart attack separately in the future."
Dr Larry B. Goldstein, director of the Duke University Stroke Center in Durham, N.C., said both heart attack and stroke are associated with inheritable factors, but the mechanism of a heart attack is usually the result of atherosclerosis, a hardening and narrowing of the arteries.
"In contrast, stroke can occur through a variety of mechanisms," he said. "Therefore, it is not entirely surprising that having a family history of myocardial infarction [heart attack] would be a stronger risk factor for having a heart attack as compared to the relationship between having a family history of stroke and stroke risk."
However, based on other studies, family history remains an important risk factor for stroke, and people who have a parent or sibling who have had a stroke, particularly at a young age, should take steps to reduce their risk, Goldstein said.
Dr Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles, added that both heart disease and stroke are to a great extent influenced by age, modifiable risk factors and lifestyle, in addition to genetics.
People should recognise that a family history of heart disease can be important information about future risk of having a heart attack, Fonarow said. "However, the absence of family history in and of itself should not be reassuring that one is at low risk for cardiovascular disease," he stressed.
For more information on heart disease and stroke, visit the American Heart Association.
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