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Study Finds Heart Disease Paradox: Black Men Have Fewer Blockages Than White Males

Posted on: Friday, 28 April 2006, 03:04 CDT

By John Fauber, Milwaukee Journal Sentinel

Apr. 28--Researchers at the Medical College of Wisconsin have raised a paradox in heart disease in black men, finding they are less likely to have severe artery blockages than white men with similar symptoms even though black men are more likely to die of heart disease.

The study suggests there might be physiological or genetic differences in the way heart disease manifests itself in African-Americans and whites and is another argument for structuring clinical trials and other medical studies so more minorities and women are included, said Sharonne Hayes, an associate professor of cardiology at the Mayo Clinic College of Medicine.

"We can't just continue to use white men as the reference," said Hayes, who was not a part of the study. "Hats off to these investigators because they looked."

The study involved 52 African-American men and 259 white men who underwent diagnosis for coronary artery disease at five Veterans Affairs hospitals, including the Zablocki VA Medical Center in Milwaukee.

Both groups underwent initial nuclear perfusion stress testing for heart disease and other assessments. They were found to have about the same likelihood of having actual coronary disease.

However, when coronary angiograms were performed, 64% of black men had an actual obstruction, compared with 77% of white men.

White men in the study were 1.8 times more likely to have at least one significant obstruction than black men, even after taking into account various other factors.

The study, which is to be published in the Journal of the American College of Cardiology in May, was presented at a medical conference Thursday.

Coronary angiography, which is considered the gold standard for detecting heart disease, involves taking an X-ray image of arteries in the heart that have been filled with a contrast material released a catheter device.

Nuclear perfusion stress testing is a less-invasive way to detect heart disease that also involves the use of a radioactive material. It can be used to help determine whether a patient should undergo an angiogram.

Other research indicates that black men are as much as 50% more likely to die of heart disease than white men, said lead author Jeff Whittle, an associate professor at the Medical College and a physician at the VA Center.

How can black men be more susceptible to artery disease while still having less of it?

Whittle said there might be other important factors beyond just the amount of blockage.

"There are a lot of things that go into having heart disease and we don't understand the half of them," he said. "With all of our testing, we still are often times surprised. People get bypass surgery and they still die."

Doctors said one possibility is that plaque buildup in the arteries of black men might be more susceptible to rupturing and causing a heart attack than in white men.

"Is it a different kind of plaque, or is it that we aren't treating African-Americans aggressively enough?" said Hayes, who also serves as director of the women's heart clinic at Mayo.

The study points to a real phenomenon, said Matthew Wolff, chief of cardiovascular medicine at the University of Wisconsin Medical School.

He noted that African-Americans with heart failure tend to respond differently to the same drugs than whites. High blood pressure also seems to play a greater role in heart failure in African-Americans than in whites while traditional coronary artery disease seems to play less of a role.

Wolff, who was not part of the study, said another possibility is that black men are more likely to have blockages in smaller vessels in the heart than in the larger arteries that are looked at in an angiogram.

Wolff said the study was intriguing and raised a lot of questions, but it does not provide new guidelines on how to treat black men.

The study also raises questions about whether stress testing is the best way to determine whether black men should go on to have a more invasive coronary angiogram, said Clyde Yancy, a professor of medicine at the University of Texas Southwestern Medical Center in Dallas.

"We assume the stress test has similar validity (in blacks and whites)," Yancy said. It might not, he said.

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Source: The Milwaukee Journal Sentinel

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