Over the past twenty years, technical advances in coronary arteriography have contributed to our understanding of the pathophysiologic aspects and natural history of coronary artery disease. Probably more than 700. 000 coronary arterio grams are performed annually throughout the world. Usually, these arteriograms are interpreted visually to determine the morphologic extent and severity of coronary artery disease. These subjective determinations, which are hampered . by relatively large intra- and interobserver variations, are used as a basis for critically important therapeutic decisions:...