Quantitative assessment of tissue prolapse on optical coherence tomography and its relation to underlying plaque morphologies and clinical outcome in patients with elective stent implantation

•We investigated native coronary lesions with normal pre-PCI CK-MB values by OCT.•Tissue prolapse (TP) after PCI was related to plaque morphologies and instability.•TP was related to transient slow-reflow phenomenon and CK-MB elevation.•Large TP volume may be useful in risk stratification of post-PCI myocardial injury.

BackgroundTissue prolapse (TP) is sometimes observed after percutaneous coronary intervention (PCI), but its clinical significance remains unclear. We investigated the relationship between TP volume on optical coherence tomography (OCT) after PCI and underlying plaque morphologies and the impact of TP on clinical outcomes.MethodsWe investigated 178 native coronary lesions with normal pre-PCI creatine kinase-myocardial band (CK-MB) values (154 lesions with stable angina; 24 with unstable angina). TP was defined as tissue extrusion from stent struts throughout the stented segments. All lesions were divided into tertiles according to TP volume. The differences in plaque morphologies and 9-month clinical outcomes were evaluated.ResultsTP volume was correlated with lipid arc (r = 0.374, p < 0.0001) and fibrous cap thickness (r = − 0.254, p = 0.001) at the culprit sites. The frequency of thin-cap fibroatheroma (TCFA) was higher in the largest TP tertile (≥ 1.38 mm3) (p = 0.015). In multivariate analysis, right coronary artery lesion (odds ratio [OR]: 2.779; p = 0.005), lesion length (OR: 1.047; p = 0.003), and TCFA (OR: 2.430; p = 0.022) were related to the largest TP tertile. Lesions with post-PCI CK-MB elevation (> upper reference limit) had larger TP volume than those without (1.28 [0.48 to 3.97] vs. 0.70 [0.16 to 1.64] mm3, p = 0.007). The prevalence of cardiac events during the 9-month follow-up was not significantly different according to TP volume.ConclusionsTP volume on OCT was related to plaque morphologies and instability, and post-PCI myocardial injury, but not to worse 9-month outcomes.