Author: SL Lee
Date: 03-27-07 06:33
Heart Pumping Variations Revealed Among African, Chinese Americans; Racial Differences May Explain Risk Levels
BALTIMORE, March 26 (AScribe Newswire) -- Generally healthy African Americans may be at higher risk of heart failure because of racial variations in heart muscle's pumping ability, a Johns Hopkins study suggests.
Scientists have known for nearly a decade that African Americans have higher rates of hospitalization for heart failure than other major U.S. racial or ethnic groups, but until now they have had limited information other than socio-economic and demographic characteristics to explain why this is so.
In what is believed to be the first, large-scale analysis of racial or ethnic differences in certain kinds of heart function, a team of Hopkins cardiologists found that muscle contraction in three main regions of the heart was on average weaker by 1 percent to 3 percent in African Americans, regardless of age, gender or existing risk factors, such as high blood pressure.
The Hopkins findings are among the first conclusions to emerge from the long-term Multiethnic Study of Atherosclerosis, or MESA for short. MESA is monitoring nearly 7,000 men and women, age 45 to 84, of different ethnic backgrounds and with no existing symptoms of heart disease to determine who develops heart failure and dies from it, and who does not.
In the study, to be presented March 26 at the American College of Cardiology's annual Scientific Sessions in New Orleans, the Hopkins team also found that Chinese Americans' hearts had a consistently, if mildly stronger squeezing function, of a similar magnitude than those of other racial or ethnic groups.
Researchers say that heart disease among Chinese Americans is less of a problem than in African Americans, although there is yet no direct evidence of a protective effect of stronger contraction in Chinese Americans.
Another surprise finding was that hearts in Chinese Americans contract more quickly than those of other ethnic groups. Three of four heart walls were fully squeezed on average 20 milliseconds to 30 milliseconds faster than in Hispanics, and were more than 10 milliseconds faster than in either African Americans or Caucasians.
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