Optical coherence tomography assessment of coronary stents 5 years after implantation for ST-elevation myocardial infarction

Background. Main causes of very late stent thrombosis are neoatherosclerosis, late malapposition and the presence of uncovered struts. However, it remains unclear how often the above-described pathological changes are determined in stable patients without adverse cardiac events. Aim. In the present study we aimed to perform optical coherence tomography (OCT) assessment of coronary stents 5 years after implantation for ST-elevation myocardial infarction. Methods. Among 194 patients included in the hospital "Prospective PCI Registry” from October 2012 to November 2013, 25 patients were enrolled in the study. All patients received OCT, median time was 66 [63.0; 72.5] months. Only stable patients without adverse cardiac events during follow-up were included in the study. The optimal condition of the coronary stents was determined in the absence of uncovered and malapposed struts, restenosis (more than 50 % of the artery diameter), signs of neoatherosclerosis and thrombus. Results. Based on OCT results, two groups were identified. The first group consisted of 9 patients (36 %) with optimal stent condition. The comparison group included 16 patients with suboptimal condition of the coronary stents. At the same time 13 patients of this group had uncovered struts, 9 - malapposed struts, 8 had both uncovered and malapposed struts, 7 patients had neoatherosclerosis, 3 patients had restenosis of more than 50 % of the vessel diameter, 1 patient - thrombus in the stented segment, 4 patients - coronary evaginations. Uncovered struts were more often found in the proximal and middle segments of the stents, while malapposed struts in the middle segments of the stents. There was direct correlation between the percent of uncovered and malapposed struts (r = 0.544; р = 0.005), percent of uncovered struts and malapposition length (r = 0.601; р = 0.002), percent of uncovered struts and maximum distance of malposition (r = 0.574; р = 0.003). The incidence of neoatherosclerosis was associated with increase in the length stents (odds ratio = 1.15, 95% CI 1.01-1.31, p = 0.039). Conclusion. In most patients, stent condition was suboptimal 5 years after implantation for STEMI. Neoatherosclerosis, malapposition and uncoated struts were the main reasons for suboptimal stent condition.