Heart Failure in African-Americans - US Cardiology 2006
Clyde W Yancy Professor of Medicine and Cardiology, and Medical Director of Heart Failure/Transplantation,
University of Texas Southwestern Medical Center
The US population is characterized by significant racial/ethnic demographic transitions with an emerging number of special populations at risk for cardiovascular disease. Amongst the special populations with heart disease, it is heart failure in African-Americans that has become the prototypical model.
Heart Failure—An Enigmatic Disease in African - Americans
Chronic heart failure is no longer a fatal diagnosis. Rather, it is a treatable disease entity with significant improvements in morbidity and mortality expected from the best application of evidence-based treatment strategies. However, a critical review of clinical trials in heart failure questions whether or not African- Americans with heart failure are able to realize these significant improvements in outcomes.This concern is, in part, driven by the inconsistent representation of African-Americans in cardiovascular clinical trials, and is further complicated by the limitations of retrospective subgroup analyses of underrepresented subgroups. Despite these important provisos, lessons have been learned from the clinical trials that define heart failure in African-Americans.
African-Americans have a higher prevalence of heart failure compared with white Americans (3% versus 2%). When heart failure occurs in African-Americans, it has an enigmatic natural history. The disease occurs at an earlier age, and both the degree of left ventricular (LV) dysfunction and apparent disease severity are worse at the time of diagnosis. Hospitalization rates are higher in African-Americans, and concerns regarding decreased survival rates have not been resolved. The imputed etiology of LV dysfunction in African-Americans is more likely to be non-ischemic than in white Americans. As seen in Figure 1, there is a lower likelihood of documented ischemic heart disease as the putative cause of LV dysfunction and a greater likelihood of nonischemic, principally hypertensive, disease as the sole potential explanation for LV dysfunction.
Figure 1: Etiology of Congestive Heart Failure in African-Americans
A number of plausible explanations for excess heart failure in African-Americans have been proposed, with no single proven causative theory.The psychosocial burdens of the African-American culture are easily recognizable and undoubtedly important, and no discussion about cardiovascular health and outcomes in African-Americans can be complete without acknowledging that healthcare disparities do exist.The deleterious influence of malignant hypertension and the burden of obesity and diabetic disease cannot be overlooked. Genomic medicine has much potential to uncover these important subgroup issues but is also quite incipient and remains problematic in interpretation.
What Clinical Trials Tell Us About Heart Failure in African - Americans
A number of major published trials have reported data as a function of race.A post hoc analysis of the Studies of Left Ventricular Dysfunction (SOLVD) treatment trial results demonstrated that mortality from heart failure was higher in African-Americans, with a 1.8-fold increase for African-American men and a 2.4-fold increase for African-American women.A subsequent reanalysis that adjusted for the degree of LV dysfunction and for trial participation (i.e. SOLVD prevention or SOLVD treatment trial) yielded no differences in mortality, but showed a significantly higher risk (44%) for hospitalization in the African-American patients compared with white patients. A suggested explanation for these findings was an apparent lower responsiveness to angiotensin-converting enzyme (ACE) inhibitors consistent with a broad statement that ACE inhibitors are less effective in African-Americans.
Conflicting data points have emerged from the clinical trial experience with β-blockers. A recent RAND Corporation meta-analysis incorporated data reported by race from the major published β-blocker trials in heart failure.Whereas the aggregate benefit of β-blockers for white Americans was a 31% reduction in mortality, the apparent benefit of β-blockers in African-Americans was only a 3% reduction.These unfavorable data are heavily influenced by the negative outcomes from the Betablocker Evaluation of Survival Trial (BEST). However, the experience with carvedilol varies substantially from the observations seen with bucindolol. In both the US Carvedilol Heart Failure Trials program and the Carvedilol Prospective Randomized Cumulative Survival Trial (COPERNICUS), retrospective analyses by ethnicity showed statistically significant benefits with carvedilol. A summary of major clinical trials in heart failure that reported data as a function of race can be found in Table 1.
Table I: Summary of Major Clinical Trials in Heart Failure Reporting Data by Race
Clyde W Yancy, MD, is Professor of
Medicine and Cardiology and the
Medical Director of Heart
Failure/Transplantation at the
University of Texas Southwestern
Medical Center. He is also the
Associate Dean of Clinical Affairs and
Director of the Cardiovascular
Institute at St Paul University
Hospital. He is a fellow of the
American College of Cardiology (ACC)
and the American Heart Association
(AHA) and a member of several
other medical societies, including the
International Society of Heart and
Lung Transplantation, the American
Society of Hypertension, and the
Heart Failure Society of America.
Dr Yancy is broadly published in the
area of heart failure, with well over
100 abstracts, manuscripts, editorials,
and book chapters to his credit,
along with an emerging presence in
Web-based educational media. He is
Associate Editor of Congestive Heart
Failure and is a reviewer for all of
the major cardiovascular journals. His
research interests include the broad
areas of clinical congestive heart
failure and heart transplantation.
Recently, he has focused on the
emerging role of registries in
cardiovascular diseases, management
of advanced heart failure with new
drugs and devices, therapeutic uses
of natriuretic peptides, and on heart
failure in special populations,
especially African-Americans. Dr Yancy
is board-certified in internal
medicine with a subspecialty in
cardiovascular disease. He earned a
medical degree from Tulane
University School of Medicine.
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