The spectrum of coronary artery disease among black African patients in South Africa is not fully understood. Studies have shown that blacks have milder coronary artery disease compared to other population groups. There is currently a paucity of local data looking at the increasing burden of this disease and the spectrum of presentation in black African populations.
The purpose of this study was to describe the spectrum of coronary artery disease in Blacks and determine if there were significant differences in severity and outcome compared to more commonly affected population groups with coronary artery disease. A retrospective chart review of Black African patients with acute coronary syndrome was performed at Grey's Hospital, with data obtained over a twenty-month period at our tertiary referral centre. Black African patients had similar coronary vessel involvement as Caucasians (single and double vessel disease), but less three vessel disease (18%).
Ultimately, the study suggests that black African patients have become a higher risk group for coronary artery disease than previously thought. It indicates that coronary artery disease is no longer an uncommon problem in blacks and that they should be considered a high-risk group of patients with cardiovascular risk comparable to Indians and whites.
Background and Literature
However, there were no racial differences in the severity of coronary artery disease among patients with at least one significant obstruction [2]. Furthermore, racial differences in coronary obstruction remained after adjustment for risk factors for coronary artery disease and characteristics of acute myocardial infarction [2]. Early case reports from the 1960s and 1970s reflect the low prevalence of coronary artery disease and myocardial infarction in black African patients during those decades.
Whites and Indians had the highest prevalence of coronary artery disease, and blacks had the lowest prevalence of coronary artery disease. More recently, increasingly severe risk factor profiles for coronary artery disease have been described in black populations. A global increase in clustering of risk factors for coronary artery disease has been described previously.
They looked at the clustering of risk factors among patients with acute coronary syndrome and significant coronary artery disease confirmed during angiography. As informative as these studies are, they are few, with data showing conflicting results regarding the overall outcomes of coronary artery disease in black African patients.
Aims and Objectives
Aim of the Study
Specific Objectives
- Objective 1
- Objective 2
- Objective 3
- Objective 4
- Objective 5
Determine the immediate outcome after thirty days in black subjects compared to Indian and white patients of the same sex and age referred for myocardial infarction during the same period.
Materials and Methodology
- Study Design
- Patient Selection
- Inclusion Criteria
- Exclusion Criteria
- Data Collection
- Ethical Considerations
- Statistical methods and analysis
Only subjects diagnosed with acute coronary syndrome who subsequently underwent coronary angiography at Gray's Hospital were included in the study. A subgroup of Indian and Caucasian patients with acute coronary syndrome matched for age and gender into separate control groups. There were 11 patients with acute coronary syndrome who did not undergo coronary angiography and were excluded.
There were seven patients with non-returnable files who were also excluded (one black African, three Indian and three white). Angiographic findings describing the location and extent of the myocardial infarction were also extracted from the file. Parameters were entered into EXCEL spreadsheets to compare the black group with the Indian and Caucasian groups.
Full ethical approval was obtained from BREC prior to initiation of the study (BREC number: BE299/12. Telephone consent was obtained from each patient during the follow-up part of the study before questions were asked. Data analysis was initiated with a check of the data for outliers , missing data and normality through skewness and kurtotis values that could affect relationships between variables.
One-way analysis of variance (ANOVA) between groups was used to compare differences in the means of individual normally distributed interval dependent variables (e.g. age) with selected categorical variables, e.g. Factorial ANOVA was used for two or more categorical independent variables (either with or without interactions). If the selected covariate was not normally distributed (based on the Shapiro-Wilk test), a non-parametric equivalent, namely the Kruskal-Wallis rank-order test of population equality, was used instead.
A Pearson chi-squared (χ2) test was used to assess significant differences in proportions of categorical cross-tabulations. If the expected number of cells in each cross-tabulation was less than 5, then a non-parametric Fishers exact test was used. Logistic regression was used to compare clinical and other characteristics by black versus Indian and Caucasian ethnicity combined.
Results
Prevalence of acute coronary syndrome
Total 79 Blacks with ACS Total 86 Whites with ACS Total 293 Indians with ACS. All 79 cases of acute coronary syndrome among black African patients were assigned to the study group. A subset of 79 Indians and 80 Caucasians of the total, matched for age 5 years and sex, were consecutively selected as comparison subjects.
Demographic data
Total number of ACS for the period n=458
Risk factor profiles
Importantly, however, the mean HDL-C was identical for all three groups at 0.9 mmol/L. Kruskal Wallis test; ┼: Adjusted for multiple test comparisons using the Simes method; ╪: Number of non-missing observations: Black, Indian, Caucasian.
Clinical data
Biochemical data
Angiographic findings
One year follow up
Estimated minimum prevalence of metabolic syndrome
For this analysis, metabolic syndrome was diagnosed according to the NCEP criteria [14]. Our statistics on the metabolic syndrome therefore most likely underestimated the true prevalence. Based on three criteria, the minimal prevalence of metabolic syndrome was equally common in the black, Indian, and white groups (52% vs. 52% vs. 59%).
Discussion
There was a strong family history of coronary artery disease among Indians and Caucasians, but only 5% of blacks had a positive family history of coronary artery disease. Early studies describing much lower rates of atherosclerotic disease as well as fewer risk factors for coronary artery disease in black African patients have already been discussed and highlight how dramatic the change has been over the past three decades, as shown in the study ours and others [15. ]. Previous studies have already reflected that blacks with coronary artery disease were younger than their Caucasian counterparts [11].
Our study confirms this, making early screening for coronary artery disease an important aspect of primary prevention in this group. More than two-thirds of the black African patients in the study were men, a finding that is consistent with previous reports that have shown that coronary artery disease is three times higher in men than women and mortality is five times higher. higher [19]. It is also worth noting that in our study, 95% of black women and 70% of men had low HDL-C levels, consistent with the presence of metabolic syndrome and diabetes, resulting in a predisposition to coronary artery disease and MI. .
The very high prevalence of low HDL-C in our black subjects with MI suggests that this may become an effective screening test to identify black African patients at high risk of coronary artery disease at an earlier time point. The estimated prevalence of metabolic syndrome in black African patients with myocardial infarction was 20% and was very similar to the Indian group (21.5%) in the study. However, the lack of documentation of waist circumference in patient files is also likely to have underestimated the true prevalence of metabolic syndrome in our study (especially as 95% of women had low HDL and nearly half of all black African patients had evidence of diabetes).
Our study clearly shows that black African patients with MI already have a high prevalence of metabolic syndrome and other risk factors for CAD comparable to Indians. This suggests that black African patients may not have warning signs such as prior angina or an established history of coronary artery disease when they present to hospital, making aggressive screening programs and control of risk factors in this group extremely important. Native Americans had the highest prevalence of three vascular diseases, which is not surprising given the high burden of diabetes and coronary artery disease in this group [ 19 ].
An analysis of the previous and current literature shows a clear difference in the spectrum of coronary artery disease among black South African patients, as depicted in Table 9, which shows the gradual increase in the prevalence of conventional risk factors for the disease of coronary arteries in black African patients. Indians and Caucasians were referred for coronary artery bypass grafting more often than blacks, reflecting the greater severity of coronary artery disease in the Indian and Caucasian groups. Furthermore, no data were found for waist circumference measurements that were likely to underestimate the prevalence of metabolic syndrome in our study.
Conclusion
Blacks had less triple vessel disease than Indians at angiography and were more likely to present at a younger age than whites, with anterior ST-segment elevation myocardial infarction, a first myocardial infarction, and without prior angina, making them a group pose a high risk. The high risk factor profile of black subjects with MI indicates that it is almost too late for primordial preventive measures in this group, as these risk factors have already been identified in the urbanized black population [15].
Cardiovascular Journal of South Africa: Official Journal for the Cardiac Society of South Africa and the Association of Cardiac Physicians of South Africa. Cardiovascular Journal of South Africa: Official Journal for the Cardiac Society of South Africa and the South African Society of Cardiologists. Differences in coronary heart disease prevalence and risk factors in African and white patients with type 2 diabetes.
Prevalence of conventional risk factors and lipid profiles in patients with acute coronary syndrome and significant coronary disease. Executive Summary of the Third Report of the National Cholesterol Education Control Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). Metabolic syndrome, undiagnosed diabetes mellitus and insulin resistance are highly prevalent in urbanized South African blacks with coronary artery disease.
Myocardial infarction redefined – a consensus document of the Joint European Society of Cardiology/American College of Cardiology Committee on the redefinition of myocardial infarction. Demographic data and outcome of acute coronary syndrome in the Asian Indian population of South Africa.
