Sones performed the first coronary artery angiogram by accident in 1958. While injecting contrast material for a left ventricular angiogram, the catheter slipped out of the ventricle and into the right coronary artery. Sones immediately recognized the advantage of visualizing the coronary artery lumen, and coronary angiography quickly developed (1, 2). Coronary angiography provided the needed diagnosis tool for new therapy, coronary artery bypass surgery (3,4). The most severe lesions could now

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... be quickly identified by the simple percent stenosis measurement (100% x [normal artery diameter -minus minimal stenotic diameter] / normal artery diameter). The percent stenosis measurement is easy to perform, can be visually estimated, and does not require quantification of the coronary artery size. This measurement together with bypass surgery became the clinical standard, which dramatically improved cardiovascular care (5). Angiographically determined percent stenosis was the unchallenged clinical standard for many years. The validity of the percent stenosis measurement was not questioned despite pathological