Cardiovascular Disease
Hypertension is a devastating illness for African Americans, among whom it appears at an earlier age and produces higher rates of mortality and morbidity when compared to white patients.
Many African American patients have biological factors which increase their vulnerability to hypertension including their greater salt sensitivity, lower plasma rennin levels and increased tendency for volume expansion.
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Current research on treatment of hypertension suggests that beta-blockers are often less effective in controlling hypertension for African Americans.
Antihypertensive Lipid-Lowering Treatment
to Prevent Heart Attack Trial (ALLHAT)
This recent study, in which 35% of the patients were African American, demonstrated the diuretic chlorthalidone:
- Was associated with greater reductions in blood pressure (BP) than the angiotensin-converting enzyme (ACE) inhibitor lisinopril
- Was also associated with a relative risk reduction in stroke compared with lisinopril
However, the increased stroke risk associated with lisinopril was experienced among African American but not non-African American patients. ALLHAT did not permit combination therapy with ACE inhibitors plus diuretics; therefore, the benefits of such regimens in this patient population could not be assessed.
Losartan Intervention For Endpoint Reduction
in Hypertension (LIFE) Study
In this study, in contrast to the overall study population, African American patients with left ventricular hypertrophy treated with atenolol were at lower risk of experiencing the primary composite end point (death, myocardial infarction, and stroke) than African Americans treated with losartan, with or without diuretics.
African American Study of Kidney Disease and Hypertension
On the other hand, in the African American Study of Kidney Disease and Hypertension, African American patients treated with the ACE inhibitor ramipril had a significantly lower incidence of the primary composite end point (glomerular filtration rate reduction, end-stage renal disease, or death) than African Americans treated with the calcium channel blocker amlodipine.
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Although the use of diuretics in African American patients may be a logical first-line choice for BP reduction, most patients will require combination therapy. African American patients with systolic BP > or =15 mm Hg above target level or a diastolic BP > or =10 mm Hg above target should be considered for first-line combination therapy.
Although certain combinations have been shown to be effective in non-African American patients, the choice of drugs for combination therapy in African American patients may be different (Ferdinand KC, 2003).
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Heart disease is more likely to cause death among African Americans than white Americans, especially among women. The age-adjusted mortality rates from heart disease for African American women are one third higher than for white women. Jha et al. (2007) studying a large cohort of women, found that African American women less often received appropriate preventative therapy and adequate risk factor control despite a greater risk for congestive heart disease event risk. The authors suggest that African American women need more effective interventions to reduce their risk factors for heart disease.
Coronary heart disease mortality is more common in African American older adults than compared to white older adults. Ethnic differences in mortality rate have been attributed to African Americans having a higher prevalence of cardiac risk factors, significant delays in seeking care, lower quality of care and inadequate access to long-term care after the acute event.
Mehta 2006 reported that African Americans compared to whites with ST-elevation myocardial infarction were significantly more likely to suffer in-hospital stroke, bleeding and 5 year mortality despite their younger age. Consistent earlier studies, Mehta et al. reported that revascularization rates were significantly lower in African Americans. Ethnic differences in utilization of this procedure were attributed to patient factors (differences in angiographic factors, patient’s preferences, and insurance/socioeconomic status) and physician’s cultural and racial biases.
African Americans’ increased vulnerability for strokes may be due to their increased prevalence of hypertension and higher systolic and diastolic blood pressures at admission and lower fibrinogen levels.
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Heart failure is a national epidemic, affecting nearly 6.2 million persons in the United States. African Americans have a higher incidence and prevalence of heart failure than members of other racial groups.
Though many studies have suggested that African American patients receive less intensive and poorer quality of care than white patients, other studies suggest that there are not significant ethnic differences in quality of care.
Rathmore et al. (2003) reported that Black Medicare patients compared to white patients hospitalized with heart failure received comparable quality of care, had slightly higher readmission rates and had higher survival rates. Left ventricular dysfunction, a common pathophysiological component of heart failure, is associated with hemodynamic abnormalities, neurohormonal activation and cellular alterations which lead to vascular and myocardial remodeling. Endothelial dysfunction and diminished nitric oxide bioavailability are also associated with heart failure.
The African American Heart Failure Trial (A-HeFT)
Current studies suggest that endothelial dysfunction and decreased bioavailability of nitric oxide may be more prevalent in African Americans. The African American Heart Failure Trial (A-HeFT) reported significantly reduced mortality after treatment with fixed doses of isosorbide dinitrate-hydralazine added to standard neurohormonal blockade. (Taylor, 2005)
This treatment intervention improved survival, decreased heart failure hospitalization rates and improved quality of life in African American patients with advanced heart failure. The results of this study results suggests that nitric oxide enhancing therapy may be an effective new treatment for heart failure.
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