Although it has long been established that a parental history of coronary heart disease contributes to risk in the child, only a maternal history appears to be important for most people, according to a presentation at the annual meeting of the American College of Cardiology.

"If doctors identify patients with a maternal history of coronary heart disease, they should compulsively look for other risk factors, such as hypertension, elevated cholesterol and obesity, and aggressively manage them," said Pamela Ouyang, MD, the study’s presenter.

Until the current study was conducted, only anecdotal evidence suggested that maternal history plays a greater role in coronary heart disease. To test the issue, researchers identified siblings of patients who had been admitted to a major American medical center with the disease. Siblings were enrolled in the study if they were less than 60 years old and not yet symptomatic. The siblings, average age 46 years, were followed for roughly 8 years.

The researchers found that if individuals had a mother with coronary heart disease, they were twice as likely to develop it themselves compared with siblings without a maternal history. If the mother had the disease when she was 55 years or younger, the individual was six times more likely to develop it. Surprisingly, the father's history had no effect unless he had the disease before the age of 45 years; in these cases, the child's risk increased fivefold.

The researchers are uncertain why a mother's history is so important. "We are still trying to figure out why," said Ouyang. "It suggests some heritable change or possibly something involving the X chromosome. The next step is to look at some of the potential genetic components."