<p><strong>Aim.</strong> The development of on a new generation of stents with abluminal biodegradable polymer is aimed at accelerating the neointimal growth and reducing the inflammatory response of the vascular wall. This article presents an analysis of healing characteristics, as assessed by optical coherence tomography (OCT), of ultrathin Synergy everolimus-eluting stent with biodegradable polymer and Xience everolimus-eluting stent with durable polymer three months after implantation.<br /><strong>Methods.</strong> In this prospective, single-center study fifty patients with significant stenosis of the left main coronary artery were randomized in 2 groups for implantation of everolimus-eluting stents with durable polymer (Xience) or abluminal biodegradable polymer (Synergy). After three months all patients underwent control coronarography supported by optical coherence tomography. A Neointimal Healing Score (NIH Score) obtained at three months after stent implantation by means of optical coherence tomography was the primary endpoint. Such OCT data as percentage of uncovered or malapposed struts only and presence of both malapposed and uncovered struts were planned as the secondary endpoints. To study the freedom from adverse events, one composite endpoint including myocardial infarction, repeat left coronary artery revascularization and death within 12 months after the procedure was determined. <br /><strong>Results.</strong> There were no significant differences in the NIH score (primary endpoint) in two groups (25.6±12.3 in Xience vs 32.5±20.3 in Synergy, respectively; p = 0.12). The struts of both types of stents showed statistically similar coverage and apposition at 3-month OCT follow-up: percentage of uncovered struts only was 6.3±3.9 and 9.9±7.8 in Xience and Synergy groups, respectively (p = 0.098) and malapposed struts only 0.25±0.5 vs 0.37±0.5; p = 0.628. The presence of both malapposed and uncovered struts was 4.9±3.8 and 5.1±4.5 in two groups and didn’t differ statistically (p = 0.92). During 12-month follow-up, two cases of stent thrombosis were recorded (one in each group), which required repeat revascularization. In addition, one case of myocardial infarction related to the right coronary artery occurred in the Synergy group.<br /><strong>Conclusion.</strong> The Synergy everolimus-eluting stent with abluminal biodegradable polymer has a healing profile comparable to that of Xience everolimus-eluting stent with durable polymer with a low rate of uncovered and malapposed struts at 3-month follow-up. A low incidence of adverse events in both groups during 12-month follow-up indicates the safety of the stents under study.</p><p>Received 18 September 2017. Revised 13 December 2017. Accepted 15 December 2017.</p><p><strong>Funding:</strong> The study did not have sponsorship.</p><p><strong>Conflict of interest:</strong> Authors declare no conflict of interest.</p><p><strong>Author contributions</strong><br />All authors contributed equally to the work.</p>