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Stable and unstable angina pectoris

Fundamental discoveries in physiology of the normal circulation, myocardial metabolism, and the pathology of coronary artery disease continue to fascinate the clinician and contribute importantly to our understanding of the mechanism of disease. Treatment, which in the past has been largely empirical, is increasingly based on sound pathophysiologic principles, some only recently elucidated. This review covers a variety of topics including endothelial function, coronary thrombosis and thrombolysis, drug treatment of coronary artery disease, enzyme leak and unstable angina, and the expanding role of coronary bypass surgery. It is increasingly clear that endothelial function, and hence, coronary vascular vasomotion is seriously disturbed in coronary artery disease. The vasoconstrictor, endothelin, is being studied intensively in a wide variety of clinical situations. Abnormal responses have been detected, eg, in atherosclerotic blood vessels in absence of ischemia. The role of incomplete thrombotic occlusion in the development of unstable angina is well recognized yet treatment designed to counteract clotting or induce thrombolysis remains unsatisfactory. Markers for thrombosis, such as fibrinopeptide-A, are being investigated in many laboratories but correlation with clinical findings has been inconsistent. Although controversial for many years, the concept of nitrate tolerance is now an established fact. The effectiveness of short-acting and long-term β-adrenergic blockers is reviewed. One interesting study demonstrates an apparent benefit of acupuncture in patients with stable angina. Extremely sensitive blood enzyme assay suggests that some patients classified clinically as unstable angina pectoris may truly have cellular damage representing micromyocardial infarction. Finally, the current status of coronary bypass surgery is reviewed. A number of recent papers describe favorable experiences following bypass operations in older patients. Ten-year follow-up of Coronary Artery Surgery Study (CASS) continues to support the view that there are no differences in long-term survival between initial medical treatment with option for later bypass grafting compared with early surgery in patients with mild angina and normal left ventricular function.