Optical coherence tomography imaging after endovascular thrombectomy: a novel method for evaluating vascular injury in a swine model

Abstract

OBJECTIVEAlthough studies have shown that some degree of iatrogenic endothelial injury occurs during endovascular thrombectomy (EVT), the clinical significance of such injury is uncertain. Furthermore, it is likely that iatrogenic effects such as endothelial denudation, intimal dissection, and tunica media edema will have varying clinical implications. The purpose of this study was to assess the feasibility of endovascular optical coherence tomography (OCT) in quantifying vessel injury in real time after EVT, correlate vessel injury with histological findings, and perform imaging at varying time intervals after EVT to assess the impact of prolonged direct exposure of the vessel to the thrombus.METHODSYorkshire swine weighing 35–40 kg were selected for use as the animal model, with a total of 9 vessels from 3 swine examined. Thrombectomy was performed using a second-generation stent retriever 1, 3, and 6 hours after thrombus deposition. The presence and degree of denudation of the endothelium, detachment and separation of the layers of the tunic media, hemorrhage within the media, dissection of the vessels, and thrombus within the lumina were assessed using OCT images acquired immediately after EVT. Bland-Altman analysis indicated that these OCT findings were correlated with postmortem histological findings.RESULTSOCT image acquisition was technically successful in all cases. Endothelial denudation was present in 65% ± 16%, 87% ± 8%, and 93% ± 7% of the vessel surface 1, 3, and 6 hours, respectively, after thrombus deposition and subsequent EVT. Residual intraluminal thrombus was present in vessels at all time intervals despite complete angiographic revascularization. Bland-Altman plots showed good agreement between OCT and histological analysis with respect to the degree of endothelial denudation and elevation, separation of the tunica media, and hemorrhage within the media. OCT appears to be more specific than histological analysis in detecting endothelial elevation.CONCLUSIONSOCT is a feasible method that can be used to assess vascular injury after EVT with histological accuracy. Varying degrees of vessel injury occur after EVT, and residual luminal thrombus can be present despite complete angiographic revascularization.