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 made. Methods & 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 (PCI) at 7 U.S. hospitals in 2011. To assess agreement, we calculated mean difference in percent diameter stenosis between clinical interpretation and QCA and a Cohen’s weighted kappa statistic. Of 216 treated lesions, median percent diameter stenosis was 80.0% (Q1 and Q3, 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 kappa of 0.27 (95% CI, 0.18 to 0.36) was found between the 2 measurements. Of 213 lesions considered ≥70% by clinical interpretation, 56 (26.3%) were <70% by QCA though none was <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 PCI as more severe than measurements by QCA. Almost all treated lesions were ≥70% by clinical interpretation, while approximately a quarter were <70% by QCA. These findings suggest opportunities to improve clinical interpretation of coronary angiography.

CorrespondenceWe appreciate the concerns raised by Drs Khandelwal and Kern about our recent analysis of the visual assessment of angiographic stenosis among percutaneous coronary intervention (PCI)-treated lesions in contemporary practice.1 In sum, their concerns involve the admittedly imperfect nature of quantitative coronary angiography (QCA), which they suggest should not be used as a tool for clinical assessments in the catheterization laboratory. We agree that QCA has limitations (and noted many of their points in our Discussion). In particular, we specifically acknowledged that QCA 'as it is currently used' does not account for many factors that should influence clinical decisions on revascularization.Nonetheless, we do believe that QCA, as an unbiased and highly reliable technique, may help quality improvement efforts by identifying (and perhaps narrowing) gaps in performance related to visual assessment. This was the overarching goal of our study, and we believe our findings strongly suggest a need to improve visual assessment. Despite several previous studies that have demonstrated deficiencies with visual assessment over the last several decades, there has been no concerted effort by the cardiology community to address extensive interobserver and intraoperator variability in the interpretation of coronary angiography. Indeed, the fact that we found significant differences across hospitals in how visual assessments compared with QCA suggests that factors other than random variability are at play. Because challenges with visual assessment in clinical practice still exist, they need to be explored and should be addressed with innovative solutions because the implications for clinical care are substantial.Both Dr Khandelwal and Dr Kern argue for assessment of the functional significance of lesions using tools like fractional flow reserve (FFR) as the better approach. We agree with this, both conceptually and in practice, and mentioned the importance of this tool in our Discussion. However, the use of FFR in our study cohort was rare, which indicates the continued reliance on visual assessment in current practice. Contemporary data from the American College of Cardiology-National Cardiovascular Data Registry CathPCI Registry also indicate that use of FFR in elective PCI is uncommon.2 In fact, as we wrote in our article, we believe that feedback and educational initiatives about visual assessment through tools like QCA may actually "enhance clinical decision making on the need for further testing (eg, FFR) before PCI." 1 We also believe that even with the widespread adoption of tools for physiological assessment of lesions like FFR, accurate visual assessment of coronary anatomy by cardiologists remains a fundamental skill required for performing coronary angiography. And we need to ensure that cardiologists are good at it.Finally, it is important to emphasize that we are not advocating for the implementation of QCA as a way to replace clinical decision making by cardiologists. Instead, we are interested in ...