Comparison of Clinical Interpretation With Visual Assessment and Quantitative Coronary Angiography in Patients Undergoing Percutaneous Coronary Intervention in Contemporary Practice: The Assessing Angiography (A2) Project

Background— Studies conducted decades ago described substantial disagreement and errors in physicians’ angiographic interpretation of coronary stenosis severity. Despite the potential implications of such findings, no large-scale efforts to measure or improve clinical interpretation were subsequently undertaken. Methods and Results— We compared clinical interpretation of stenosis severity in coronary lesions with an independent assessment using quantitative coronary angiography (QCA) in 175 randomly selected patients undergoing elective percutaneous coronary intervention at 7 US hospitals in 2011. To assess agreement, we calculated mean difference in percent diameter stenosis between clinical interpretation and QCA and a Cohen weighted &kgr; statistic. Of 216 treated lesions, median percent diameter stenosis was 80.0% (quartiles 1 and 3, 80.0% and 90.0%), with 213 (98.6%) assessed as ≥70%. Mean difference in percent diameter stenosis between clinical interpretation and QCA was 8.2±8.4%, reflecting an average higher percent diameter stenosis by clinical interpretation (P<0.001). A weighted &kgr; of 0.27 (95% confidence interval, 0.18–0.36) was found between the 2 measurements. Of 213 lesions considered ≥70% by clinical interpretation, 56 (26.3%) were <70% by QCA, although none were <50%. Differences between the 2 measurements were largest for intermediate lesions by QCA (50% to <70%), with variation existing across sites. Conclusions— Physicians tended to assess coronary lesions treated with percutaneous coronary intervention as more severe than measurements by QCA. Almost all treated lesions were ≥70% by clinical interpretation, whereas approximately one quarter were <70% by QCA. These findings suggest opportunities to improve clinical interpretation of coronary angiography.