In vivo quantitative assessment of atherosclerotic plaque: A validation study on the optical coherence...

Growing evidence indicates that coronary plaque instability is an independent risk factor for adverse coronary events, yet current optical coherence tomography (OCT) assessment of high-risk plaque characteristics (HRPC) relies largely on qualitative interpretation. The index of plaque attenuation (IPA) is a quantitative OCT-based metric that may provide a more objective evaluation. This retrospective observational diagnostic accuracy study assessed the performance of OCT-derived IPA for HRPC detection in patients with acute coronary syndrome or stable angina, using expert consensus qualitative OCT analysis as the reference standard. A total of 560 analyzable OCT cross-sections from 83 patients were categorized as HRPC or non-HRPC, with the latter grouped into progression plaque characteristics (PPC) or normal vessels. Receiver operating characteristic analysis was performed. IPA11 distinguished HRPC from non-HRPC with an area under the curve of 0.75 (95% confidence interval: 70.3-79.0; P < .001), sensitivity of 76.1%, and specificity of 63.8%. IPA11 was higher in HRPC than in non-HRPC (66.0 [38.0-110.0] vs 20.0 [2.0-52.0]; P = .001). In the non-HRPC group, IPA8 differentiated PPC from normal vessels with an area under the curve of 0.98 (95% CI: 95.3-98.8; P < .001), with higher values in PPC (241.0 [155.5-320.5] vs 11.0 [3.5-30.5]; P < .001). IPA offers an objective, quantitative method for automated OCT-based plaque assessment, demonstrating good accuracy for HRPC identification and excellent discrimination of PPC from normal vessels, meriting validation in larger prospective studies.