Afro-Americans with high blood pressure have double the risk of enlarged heart

Left ventricular hypertrophy (LVH) is an increase in muscle mass of the heart’s left pumping chamber.  It results from thickening of the heart muscle due to high blood pressure, valve disease or other conditions that increase the heart’s workload.

“LVH is a strong predictor of adverse outcome, including heart attack, stroke and death,” said lead author Jorge R. Kizer, M.D., M.Sc., an assistant professor of medicine and public health at Weill Medical College of Cornell University and an assistant attending physician at New York-Presbyterian Hospital.

In the study of 1,060 blacks and 580 whites, blacks had higher average left ventricular mass index and relative wall thickness than whites.  These differences persisted after adjustment for age, gender,and clinical risk factors such as blood pressure, time since blood pressure diagnosis, high blood pressure treatment and artery stiffness.  The prevalence of left ventricular hypertrophy in blacks was nearly twice that of whites and concentric geometry (increase in wall thickness without accompanying cavity enlargement) among blacks was two-and-a-half-times that of whites, researchers said.  This was the case after accounting for additional factors such as socioeconomic level, education, smoking and cholesterol status.

In an accompanying editorial Mark H. Drazner, M.D., M.Sc., an associate professor of medicine at the University of Texas Southwestern Medical Center at Dallas, said the study offers the most convincing data to date that blacks are more likely to develop left ventricular hypertrophy.

“Blacks have higher rates of cardiovascular mortality and this study may point out an area that can explain this difference in mortality.  It also may point the way for therapies that can minimize ethnic disparities in outcome,” he said.

Kizer and colleagues studied measurements of left ventricular mass and geometry in patients enrolled in the Hypertension Genetic Epidemiology Network (HyperGEN), which is part of the National Health, Lung, and Blood Institute Family Blood Pressure Program.  HyperGEN enrolled siblings who had high blood pressure – systolic pressure greater than 140 mmHg and/or diastolic pressure of 90 mmHg or higher – by age 60.  The patients had left ventricular mass measured by echocardiography.

Kizer said studies suggest that some high blood pressure medications, such as angiotensin receptor blockers or ARBs, achieve greater regression of LVH than others.  But, the largest of such studies failed to show the same corresponding reduction in cardiovascular events in blacks as occurred in whites.

“How to translate information about specific drugs into treatments for blacks is still uncertain,” he said.  “However, the higher prevalence of cardiac hypertrophy among hypertensive blacks supports the need for improved attainment of blood pressure goals in accordance with published guidelines.”

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VII) defines normal blood pressure as a systolic pressure of less than 120 mm Hg and a diastolic pressure of less than 80 mm Hg.

Kizer co-authors are Donna K. Arnett, Ph.D.; Jonathan N. Bella, M.D.; Mary Paranicas; D.C. Rao, Ph.D.; Michael A. Province, Ph.D.; Albert Oberman, M.D., M.P.H.; Dalane W. Kitzman, M.D.; Paul N. Hopkins, M.D., M.S.P.H.; Jennifer E. Liu, M.D.; and Richard B. Devereux, M.D.

The study was partly funded by the National Heart, Lung, and Blood Institute and the National Institutes of Health.

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