The underlying coronary lesion in myocardial infarction: implications for coronary angiography.

Myocardial infarction is usually caused by sudden thrombotic occlusion of a coronary artery at the site of a fissured atherosclerotic plaque. Recent evidence suggests that coronary angiography may be insensitive in detecting and quantitating atherosclerosis. Serial angiographic studies demonstrate that the majority of myocardial infarctions occur due to occlusion of arteries that previously did not contain angiographically significant (greater than 50%) stenoses. Similarly, quantitative angiography performed after thrombolytic therapy indicates that the coronary lesion underlying the clot is frequently not severely stenotic. Thus, an angiographically apparent stenosis is not necessary for the development of a thrombotic occlusion resulting in an MI. These observations suggest that coronary angiography does not accurately predict the site of a subsequent occlusion that will produce a myocardial infarction.