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Although much recent attention has focussed on the events of the first 12 hours of acute myocardial infarction, the local and systemic evolutionary changes which occur during the following days and weeks are of equal importance. The condition of the ischaemic and in-farcted myocardium may be altered by spontaneous reperfusion or reocclusion, with effects on the mechanical and electrical sequelae of the initial infarction. The area of infarction undergoes “maturation” in its mechanical and electrical properties, which result in alterations in ventricular function and in the types of arrhythmias encountered. These changes occur against the background of the metabolic and neurohumoral response to infarction, which result in changes in catecholamine drive, plasma potassium, and free fatty acid levels, and in the renin-angiotensin-aldosterone system. The resolution of the initial metabolic response to infarction may be slowed or reversed by the development of heart failure. The varying speed of these adaptive processes has considerable influence on the optimal timing of investigations designed to identify “high-risk” patients. The appropriate time for the start of secondary prevention measures will likewise depend on the restoration process following the initial infarct.