African Americans are disproportionately affected by heart failure and have not experienced the same benefit from treatment as white patients have. Much of the disparity can be blamed on modifiable risk factors such as uncontrolled hypertension and on suboptimal health care. When African Americans are treated according to guidelines, discrepant outcomes can be minimized.
In this article, we review the processes contributing to heart failure in African Americans, its management, and challenges with regard to disparities.
HEART FAILURE IS INCREASING
Despite 20 years of progress in understanding the pathophysiology of heart failure and developing medical and surgical therapies for it, its prevalence and associated morbidity are increasing in the United States. In 2010, 6.6 million (2.8%) of the adults in the United States had heart failure,1 and the prevalence is expected to increase by about 25% by 2030.
DISPARITIES IN INCIDENCE, OUTCOMES
Heart failure is more prevalent in African Americans than in whites, imposes higher rates of death and morbidity, and has a more malignant course.1–6
According to American Heart Association statistics, the annual incidence of heart failure in whites is approximately 6 per 1,000 person-years, while in African Americans it is 9.1 per 1,000 person-years.1 In the Atherosclerosis Risk in Communities study, the incidence of new heart failure was 1.0 per 1,000 person-years in Chinese Americans, 2.4 in whites, 3.5 in Hispanics, and 4.6 in African Americans.2
Moreover, when hospitalized for heart failure, African Americans have a 45% greater risk of death or decline in functional status than whites.7
Heart failure also occurs earlier in African Americans. Bibbins-Domingo et al8 reported that heart failure before age 50 was 20 times more frequent in African Americans than in whites. Functional and structural cardiac changes appeared an average of 10 years before the onset of symptoms and were strongly associated with the development of subsequent heart failure.8
In the Women’s Health Initiative, African American women had higher rates of heart failure than white women, perhaps in part because of higher rates of diabetes.9
Heart failure with preserved ejection fraction
About half of patients who have signs and symptoms of heart failure have a normal (“preserved”) ejection fraction. The incidence of this condition, previously called diastolic heart failure, appears to be similar between African Americans and whites. However, African Americans appear to have a greater incidence of factors that predispose to it and tend to present later in the course.10 For example, African Americans have higher left ventricular mass and wall thickness and a higher incidence of left ventricular hypertrophy than white patients.11–13 In addition, those with heart failure with preserved ejection fraction tend to be younger, female, more likely to have hypertension and diabetes, and less likely to have coronary artery disease, and tend to have worse renal function than their white counterparts.14,15 The predisposition to diastolic impairment persists even after adjusting for risk factors.11–15 The mortality rate in African Americans with heart failure with preserved ejection fraction and without coronary artery disease may also be higher than that of comparable white patients.16
WHY DO AFRICAN AMERICANS HAVE MORE HEART FAILURE?
Modifiable risk factors
In African Americans, the higher percentage of cases of heart failure is attributable to modifiable risk factors such as hypertension, hyperglycemia, left ventricular hypertrophy, and smoking, and fewer cases are due to ischemic heart disease.2,3 Nonischemic cardiomyopathy predominates in African Americans, whereas ischemic cardiomyopathy predominates in whites.
Hypertension, diabetes, obesity, and chronic kidney disease all portend subsequent heart failure and are common in African Americans, but hypertension is the main culprit.3,5,8,17–21 The prevalence of hypertension in African Americans is among the highest in the world, and because African Americans are more likely to have poorer control of their hypertension, they consequently have more target-organ damage.22 Indeed, in many hypertensive African Americans who develop heart failure, the hypertension is poorly controlled. However, even after adjusting for risk factors, and particularly blood pressure control, African Americans remain at higher risk of heart failure.23
The specific mechanistic links between hypertension and heart failure remain to be identified. Despite having a higher prevalence of left ventricular hypertrophy and left ventricular remodeling, African Americans with heart failure tend toward systolic heart failure, as opposed to heart failure with preserved ejection fraction.
Neurohormonal imbalances and endothelial dysfunction
Derangements in the renin-angiotensin-aldosterone and adrenergic axes are likely the main pathophysiologic mechanisms in the genesis of heart failure in all populations. However, other factors may underlie the enhanced disease burden in African Americans.
Impaired endothelial function, as evidenced by impaired digital and brachial artery vasomotion, is very common in African Americans.24–26 The small arteries of African Americans are less elastic than those of whites and Chinese.27 The underlying mechanism may be related to increased oxidative stress, decreased nitric oxide availability, exaggerated vasoconstrictor response, and attenuated responsiveness to vasodilators and nitric oxide.28–31