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Across the world, parents pass on heart risks

Having a parent with a history of heart disease almost doubles a person's risk of also getting heart disease, no matter the person's ethnicity or home country, according to a new study.
/ Source: Reuters

Having a parent with a history of heart disease almost doubles a person's risk of also getting heart disease, no matter the person's ethnicity or home country, according to a new study.

Heart disease kills more than 7 million people worldwide every year. While previous studies have confirmed the relationship between a family history of heart disease and a person's own heart risk in certain populations, the new research suggests that the effect of family history is about the same in cultures across the world.

The study also suggests that if your parents had a heart attack, changing your behavior to a more-healthy pattern, while helpful, isn't guaranteed to protect you completely. That's because people whose parents had a heart attack were still more at risk themselves after many known factors associated with heart disease were accounted for, including diet and lifestyle choices, as well as some genes known to be involved in heart disease.

"This study reinforces the important role of family history as one of the very important risk factors, in addition to other known modifiable risk factors," Dr. Christopher O'Donnell, who studies heart disease at the National Institutes of Health and was not involved in the current study, told Reuters Health. It "reinforces the need to integrate the family history into the day-to-day practice of prevention and therapy for heart disease."

The new findings are the latest from the INTERHEART study, which was led by Dr. Salim Yusuf of McMaster University in Ontario, Canada and involved patients in 52 countries on every continent except Antarctica. Altogether it included about 12,000 patients who were being treated for their first heart attack in 1999-2003, and about 15,000 people of the same age and sex with no history of heart disease who were used for comparison.

About 18 percent of study patients who had suffered a heart attack also had a parent with a history of heart attack, compared to 12 percent of participants without heart disease, according to the findings, which are published in the Journal of the American College of Cardiology.

When the researchers factored in the patient's age, sex, and region of residence, those who had at least one parent with a history of heart disease were still 1.8 times more likely to get heart disease themselves — a number that was consistent across different ethnicities and world regions. The risk was the same whether it was an individual's mother or father who had the heart attack, but higher if both parents were affected or if either or both parents had a heart attack before the age of 50.

Accounting for known heart disease risk factors including smoking and alcohol consumption, fruit and vegetable consumption, and obesity didn't explain the increased risk that comes with having a parent with heart disease. And when the authors tested some of the participants for eight genes that have been implicated in heart disease, genetic differences still did not explain that risk.

That could be because there are so many small but important factors in behavior, diet, and lifestyle that play a part in explaining why people whose parents had heart disease are more likely to get heart disease themselves — including many factors that haven't been discovered yet. There could also be hundreds or even thousands of genes that play some role in determining a person's risk of heart disease when they are passed from parent to child, doctors say.

"We know that family history represents many things," said Dr. Themistocles Assimes from the Stanford University School of Medicine, the author of an editorial accompanying the study. "A lot of those things are genetic. Some are almost certainly environmental (factors) that we don't know about that we can't measure," he told Reuters Health.

But, Assimes added, this study showed that "the excess risk associated with family history is about the same everywhere. Whatever those things are that are unknown, they average out to be about the same in terms of increasing risk."

Despite the many questions that still exist about how heart disease risks are shared between generations, just knowing that those risks are there can help doctors in different parts of the world prevent heart disease in their patients.

"A family history is a very cheap, simple thing to (find out about)," Dr. Erin Michos, a cardiologist at the Johns Hopkins School of Medicine who was not involved in the study, told Reuters Health. "You don't have to measure anything, there's no lab tests."

When you put that together with the fact that doctors, both in the developing and developed world, are getting better at being able to determine who has suffered even a small heart attack, linking parents and children to predict who is likely to get heart disease is only going to get more accurate, Assimes said.