Angiographic definition of critical coronary artery stenosis.

In summary, it is hazardous to rely solely on coronary angiography to define critical coronary stenosis. Clinically, the physiologic significance of a narrowing observed at coronary angiography can best be evaluated by obtaining additional evidence of myocardial ischemia, i.e. stress testing with ECG monitoring, resting and exercise isotope perfusion studies or ventriculographic studies. However, when evaluating coronary angiograms for critical coronary stenosis, several points are worth considering. First, a long narrowing will decrease coronary blood flow more than a short narrowing of the same severity. Second, sequential narrowings will decrease coronary blood flow more than a single narrowing of the same total length. Third, a long narrowing can be estimated more accurately than a short narrowing. Fourth, caliper measurements of coronary artery narrowings are more accurate than subjective estimation, and fifth, coronary artery dilators may increase the percentage narrowing in some cases. The complex effects of percent stenosis and length of stenosis on the physiology of coronary blood flow must always be considered when evaluating angiograms. In addition, the angiographic or photographic artifacts produced by short narrowings tend to overestimate the percent stenosis and, thus, calipers should be used to measure percent stenosis, especially in the short narrowings.