OF COMMITEE ON GRADING LESIONS , COUNCIL ON ARTERIOSCLEROSIS , AMERICAN HEART ASSOCIATION Grading Stenosis in the Right Coronary Artery

A committee of pathologists compared four methods of evaluating coronary artery stenosis in the first 6 cm of 30 right coronary arteries. Seven judges twice estimated the percent reduction in lumen and the length of stenosed artery in longitudinally opened arteries, in postmortem angiograms, in casts, and in the three media together. The mean of 14 replicate estimates (seven judges, two rounds) based on the composite media was considered the "truest" value for each artery. Estimates based on casts correlated best with those based on the composite media. Estimates based on arteries and angiograms were consistently lower than those based on casts or on the composite media. Reliability was worst for estimates based on the arteries, intermediate for estimates based on angiograms and the composite media, and best for estimates based on casts. There was significant bias among judges in estimates based on single media, except in length stenosed based on arteries and angiograms. There was also significant bias among judges in both measures of stenosis based on the composite media. Percent reduction in lumen is correlated with length of artery stenosed. When more than half of the first 6 cm is stenosed, the lumen reduction approaches 100%. Either of the two measures, any one of the three single media, or any combination of the three media may be useful in evaluating coronary artery stenosis. Choice of the method depends on the requirements of the study. Artery, angiogram, and cast together seem indicated when clinicopathological correlation is the purpose of the investigation. An investigator must establish the reliability and validity of any method chosen under the conditions of his study.