PRIMARY AND SECONDARY PREVENTION OF MYOCARDIAL-INFARCTION AND STROKES- AN UPDATE OF RANDOMLY ALLOCATED, CONTROLLED TRIALS

Aim: To summarize the risk factors associated with coronary heart dise ase and strokes and to evaluate measures used in the prevention and tr eatment of these diseases. Method: A review of the results of randomly allocated clinical trials of treatment for both primary and secondary prevention of coronary heart disease and strokes. Results: Reductions in elevated blood pressure and cholesterol and cessation of cigarette smoking have clearly been shown to reduce the incidence of coronary h eart disease. A reduction in blood pressure has also been shown to red uce the risk of strokes. In addition to other classical risk factors, such as abnormal serum lipids, diabetes and a genetic predisposition, recent studies have shown that elevated levels of fibrinogen and other clotting factors, elevated levels of renin and decreased levels of an ti-oxidant vitamins such as E, C and beta-carotene can predict coronar y heart disease and strokes. Thrombolytic therapy, aspirin and beta-bl ockers have been shown to reduce mortality in patients with myocardial infarction, and the latter two agents reduce mortality, re-infarction and strokes with long-term use. Treatment with intravenous magnesium and nitrates has shown promise but larger trials are required to confi rm the results. Both aspirin and heparin have proven value in reducing the incidence of myocardial infarction and death in unstable angina. Following an acute myocardial infarction, long-term therapy with aspir in, beta-blockers, lipid-lowering agents and oral anticoagulants has b een shown to reduce mortality and re-infarction. In patients with larg e infarcts associated with a low ejection fraction or heart failure, t he use of angiotensin converting enzyme (ACE) inhibitors reduces morta lity, hospitalization for heart failure and re-infarction. The use of diuretics to lower blood pressure reduces strokes. In contrast, calciu m antagonists do not appear to consistently reduce mortality or preven t vascular events when used for primary or secondary prevention of eit her myocardial infarction or strokes. Conclusions: Myocardial infarcti on and strokes can be prevented by refraining from smoking and maintai ning appropriate blood pressure levels and a favourable balance of lip ids. Following a myocardial infarction, further drug treatment should include aspirin, thrombolytic therapy (in acute myocardial infarction) , beta-blockers, ACE inhibitors (in patients with a low ejection fract ion) and perhaps anticoagulants.