Acute myocardial infarction in a young South African Indian-based population: patient characteristics on admission and gender-specific risk factor prevalence.

BACKGROUND: Myocardial infarction (MI) is a complex disease caused by interaction of a number of genetic and environmental factors. This disease has reached epidemic proportions in South African Indian descendants. The aim of this study was to survey the prevalence of coronary heart disease risk factors in a sub-group of young Indian patients (< or = 45 years) who presented to the Coronary Care Unit at the R. K. Khan Hospital in Durban, a major referral centre for patients with acute MI in the province of Natal. METHODS AND RESULTS: A total of 245 patients < or = 45 years of age were recruited from patients consecutively admitted to the Coronary Care Unit at the R. K. Khan Hospital, Durban, KwaZulu Natal, South Africa between 1996 and 1999 with a diagnosis of acute MI. All patients were of Indian origin living in the Durban area in the province of KwaZulu-Natal. Demographic and risk factor data were obtained from all patients and included anthropometric measures, family history and the traditional cardiovascular risk factor assessment (smoking, lipids, hypertension, and diabetes mellitus). Clinical data included in-hospital presentation, management and complications and angiographic classification of coronary atherosclerosis. The most prevalent risk factors were previous: smoking (74%), and hypertriglyceridaemia (54%). Only 14% of the population presenting with an acute MI were women. Smoking was more common among men (81%) than in women (35%). Abnormal high density lipoprotein (HDL) cholesterol levels were detected in 38% of the patients with a dear gender difference: 43% and 9%, in men and women, respectively. In contrast hypertension was more prevalent in young women with MI than in men: 38% and 19%, respectively. Coronary angiography was performed in 79 patients on admission; a single vessel stenosis was found in 28%, two vessel disease in 20% and triple vessel disease in 52%, respectively. On admission, 92% of patients were in Killip class I. Overt heart failure and cardiogenic shock were uncommon and were seen in 3.3% and 0.8%, respectively. Patients who received thrombolytic therapy had fewer complications (8%) compared to those who did not (11%). However, the difference towards a benefit of thrombolysis did not reach significance. Recurrent angina (6%) was the commonest complication, while ventricular arrhythmias were observed in 2% of patients. There was a strong familial link: 54% of the patients had a family background of coronary heart disease (CHD) while 42% and 41% had family members who suffered from diabetes mellitus and hypertension, respectively. CONCLUSION: Smoking and dyslipidaemia (predominantly hypertriglyceridaemia, and low HDL-cholesterol) were the most common cardiovascular risk factors of MI in young South African Indians. A strong familial link was observed not only for a history of CHD/MI, but also for hypertension and diabetes mellitus, supporting a genetic basis for the development of premature CHD. Therefore, further analysis of potential genetic factors such as variance of genes involved in vascular homeostasis, haemostatic factors, lipid metabolism and other metabolic factors seems warranted.

Cigarette smoking is independently associated with markers of endothelial dysfunction and hyperinsulinaemia in nondiabetic individuals with coronary artery disease.

BACKGROUND: Oxidative stress and endothelial dysfunction have been introduced as a unifying pathological mechanism for early atherosclerotic disease. They are caused by a variety of stimuli including cigarette smoking (environmental) and type 2 diabetes (disease factor). However, the role of hyperinsulinemia, a marker of insulin resistance, as a risk factor for atherosclerosis remains to be clarified. STUDY OBJECTIVES: To study the relationship of smoking, hyperinsulinaemia and biochemical markers of oxidative stress and endothelial dysfunction, in patients with coronary artery disease. DESIGN: Case-control study of 5-year survivor status in smokers, former smokers and nonsmokers with angiographically documented stable coronary artery disease classified by self-reporting of smoking status together with plasma cotinine measurements. SETTING: Cardiology and cardiac surgery unit of a tertiary care referral centre. PATIENTS AND METHODS: Plasma levels of vitamins C, E and selenium, and the adhesion molecules E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were assessed in 214 patients at baseline together with the glucose and insulin response to an oral glucose challenge. Sixty known or newly diagnosed type 2 diabetic patients (28%) were identified and excluded from further analysis. RESULTS: E-selectin and ICAM-1, serving as markers of endothelial dysfunction, significantly correlated with hyperinsulinaemia (p < 0.05). Circulating immunoreactive insulin was elevated in active smokers and former smokers as compared to non-smokers after an oral glucose load (p < 0.05 for the area under the insulin time curve), despite a similar glucose response. Smoking was associated with a decrease in antioxidant vitamins C (p = 0.02) and E (p = 0.03), and an increase of E-selectin (p < 0.05) and ICAM-1 (p < 0.001). Low baseline ICAM-1 and high vitamin C levels emerged as the most significant multivariate predictors of 5-year survival (p < 0.001). CONCLUSIONS: Hyperinsulinaemia in smokers is linked with markers of endothelial dysfunction. Impaired vascular reactivity can thus be a new possible mechanism linking insulin resistance and smoking.