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 non-ischemic, principally hypertensive, disease as the sole potential explanation for LV dysfunction.
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.