Is race a factor in heart health?

Doctors also weigh genes, environment

April 01, 2007|By Chris Emery | Chris Emery,sun reporter

Claudia E. Langley received a new heart last fall after 10 years of coping with one that was failing.

"I was looking at death's door," she recalled. "I thank God for each hour, for each day."

Experts have long known that African-Americans like Langley are at greater risk of heart failure than other groups. New findings emerging from a large-scale study of race and cardiovascular disease promise to shed light on the underlying reasons for the disparity.

Using data from that project, Johns Hopkins researchers have finished two newly released studies that together suggest the problem is rooted in environmental as well as genetic factors.

One study measured heart strength and found that African-American heart contractions were slightly weaker than those of other races.

"Weaker muscles make you more at risk for sudden death and heart failure," said Dr. Veronica Fernandes, a postdoctoral researcher at the Johns Hopkins University School of Medicine who presented the findings.

She said the results suggest heart failure rates might in part be explained by genetics - a conclusion questioned by other scientists, who say race is a poor proxy for genetic heritage. People who appear to be of the same race or ethnic group don't necessarily carry the same genes.

The other study found African-Americans' risk for heart failure is on average nearly twice that of Caucasians and nearly five times that of Chinese-Americans.

High rates of diabetes and high blood pressure among blacks may explain their greater heart failure risk, the researchers concluded.

Both studies drew from the Multi-Ethnic Study of Arteriosclerosis, a long-term cardiovascular health study taking place in six communities around the United States, including Baltimore. It began tracking the cardiovascular health of nearly 7,000 men and women between the ages of 45 and 84 in 2000 and is planning to follow them until 2008.

Experts hope further research from the project will chip away at the mystery of differences in cardiovascular health among the races.

"There are some intriguing race-related issues," said Dr. James Porterfield, chief of cardiology at Greater Baltimore Medical Center. "There are clearly both environmental factors and genetic factors, but there is a lot to be learned."

Dr. Hossein Bahrami, a cardiology fellow at Johns Hopkins who worked on the study of the comparative risk of heart failure, said diabetes and high blood pressure stood out as likely culprits. African-Americans are at greater risk than Caucasians for the conditions, and both of them can damage the heart if not properly treated.

Bahrami proposed that lack of proper treatment for the disorders may contribute to heart failure in blacks. That argument is bolstered by a puzzling fact: Blacks have fewer heart attacks, but a worse prognosis once they do have one.

A heart attack is an interruption in blood flow to the heart muscle, which can contribute to heart failure, a chronic inability of the heart to pump adequate amounts of blood.

"Maybe African-Americans don't receive the proper management after a heart attack," Bahrami said, "and that leads to heart failure."

More than 287,000 Americans die each year of heart failure, according to the American Heart Association.

The rate of death in blacks with heart disease is higher than that for whites. Black men, for instance, die at a rate of about 23 per 100,000, while 20 of every 100,000 white men die of heart failure.

Dr. Elijah Saunders, a professor at the University of Maryland School of Medicine, said doctors often don't follow treatment guidelines as rigorously as they should for minorities. "Research has shown the quality of care is not as good as it is for whites," he said.

Encouraging doctors to aggressively diagnose and treat black patients for hypertension and diabetes, he said, might make a difference. He also thinks doctors should make sure that they thoroughly educate black patients on how to manage the disorders.

Saunders added, however, that doctors are only part of the problem. Patients' motivation, economic status, access to care, and insurance coverage all play a role, he said.

Yet Saunders thinks that genetic differences may also play a part. In the study of racial differences in heart strength, magnetic resonance imaging (MRI) was used to determine the strength of heart muscle contractions.

Chinese-Americans on average had the strongest and fastest contractions; those of Caucasians and Hispanics were slightly weaker. African-Americans had the weakest contractions, by 1 percent to 3 percent.

The Hopkins researchers said they controlled for environmental factors, so the difference in heart strength was likely rooted in genetics.

Previous studies have linked weakening of heart muscle with heart failure and sudden cardiac death, which results from abrupt loss of heart function.

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