Cardiovascular Disease in Racial and Ethnic Minorities

Abstract

Large epidemiological Studies have helped define differences in majority and minority population health risks and outcomes. The National Health and Nutrition Examination Survey (NHANES) observed African-American, Mexican American, and white non-Hispanic women from 1988 to 1994 and found a striking prevalence of abdominal obesity and metabolic syndrome in both African-Americans and Mexican Americans. The Multi-Ethnic Study of Atherosclerosis (MESA) was designed to Study the prevalence and progression of sub-clinical CVD in multiple ethnicities including whites. The rate of awareness of CVD as the leading cause of death has nearly doubled among women since 1997. Awareness of heart disease is independently correlated with increased physical activity and weight loss. The NHANES study shows that the prevalence of obesity, which can be associated with insulin resistance, is highest in non-Hispanic black women. The Women's Health Initiative (WHI) has shown that the major correlates of HTN among postmenopausal women were black race, CVD, physical inactivity, and excess alcohol consumption. There was also evidence that blood pressure control decreased with age. The Dallas Heart Study has shown that left ventricular hypertrophy (LVH) is two- to three-fold more common in African-American women compared to Caucasian women. About 30% of women in America do not perform any leisure-time physical activity (Centers for Disease Control and Prevention. http://www.cdc.gov/nchs/data/nhis/earlyrelease/200709-07.pdf;). This percentage is higher in women with less than a high school education or lower income groups. Women respond better to lifestyle physical activity recommendations vs structured exercise recommendations. For many women, a home-based format for physical activity which would accommodate their caregiver and work roles would be more advantageous over more traditional sessions in a gym or health club. When adjustment for lipids, diabetes, and HTN were made, elevated levels of CRP still remained a predictor of increase risk of CAD with a RR Of 1.68 (Pai et al. N Engl J Med 351:2599-2610, 2004). Anemia, which is much more prevalent in women, is associated with adverse CV consequences by increasing preload and reducing afterload and in the long term, resulting in LVH. The WHS found no benefit of adding 600 IU of vitamin E supplementation every other day on reduction of major CV events or cancer, as well as overall survival benefits. The Primary Prevention Project enrolled 4495 patients (2583 women with a mean age of 64.4 years) with one or more risk factors for CVD. This trial found that 100 mg of aspirin/day lowered CV death by 44% and total CV events by 23%. By contrast, the WHS found that in healthy women 45 years and above, 100 mg of aspirin every other day did not affect the risk of myocardial infarction or death from CV causes but lowered the risk of stroke. Compared to the WHS, the Primary Prevention Project was an open label study which enrolled older patients (mean age 64.4 years compared to 54.6 in WHS), with at least one CV risk. These factors may explain the variable effect of aspirin found in these two studies. Multiple observational studies suggested that estrogen replacement in postmenopausal women decreased heart disease risk by 50%. However, new randomized studies have addressed the issue of hormone replacement in menopausal women. Exercise electrocardiographic evaluation has lower sensitivity and specificity in detecting obstructive CAD in women: 61 and 70% as compared to 70 and 77% in men. Despite this, prognostic information can be derived from exercise testing. Exercise duration is the strongest predictor of long-term outcomes. Because of the limitations of exercise stress electrocardiography in women, concomitant imaging has been tested. The positive predictive value is lower in women compared to men (66% vs 84%) which may be a reflection of the lower prevalence of obstructive CAD in women who were tested. Pharmacologic stress testing such as dobutamine stress echocardiography (DSE) can be done in patients that cannot exercise. Women who cannot exercise should undergo pharmacologic stress testing or dobutamine echocardiography, which has the highest combination of sensitivity and specificity. Cardiovascular disease in women is very unique in that there is greater symptom burden, despite a lower prevalence of obstructive CAD by coronary angiography as compared to men. The pathophysiology of chest pain with non-obstructive epicardial CAD is very variable. Some patients have non-cardiac chest pain, while others have endothelial dysfunction, variant angina, or an overlap of these conditions. Even though women bear about 50% of the burden of heart failure in the United States, their representation in the randomized controlled heart failure trials has been about 20% and it has not changed over the past two decades.