Bioresorbable Polymer Coated Metallic Stents and Fully Bioresorbable Scaffolds: Benefits and limitations in different coronary lesion subsets, -clinical and intracascular imaging results-

Percutaneous coronary intervention (PCI) which involves the deployment of devices such as metallic drug eluting stents (DES) in coronary artery lesions and concomitant dual antiplatelet therapy (DAPT) is one of the mainstays of management of coronary artery disease and has become one of the most common treatment procedure in contemporary medicine.
Despite relatively good clinical results, contemporary metallic DES still face limitations such as a cumulative lifelong risk of restenosis requiring revascularisation and mechanical issues such as long term risk of strut fracture. Newer devices have since emerged such as newer generation DES with very thin struts with bioresorbable polymer as well as completely bioresorbable vascular scaffolds (BRS) which represent a novel approach in the treatment of coronary artery disease, by initially performing the function of metallic DES and yet having the potential for eventual device resorption avoiding a permanent nidus for very late clinical events.
This thesis aims to investigate the outcomes and limitations of DES with bioresorbable polymer and BRS in the different clinical scenarios and lesions subsets using a combination of advanced imaging modality (Optical Coherence Tomography) and clinical registries to evaluate device performance such as BRS in specific clinical settings and larger patient populations respectively.
OCT has been used to evaluate emerging technologies such as BRS and has become a safe and standard imaging modality to evaluate acute stent or scaffold performance in simple and complex lesions such as calcified lesions. While BRS implantation was associated with good acute procedural outcomes and satisfactory vessel healing at 6 months in certain clinical subsets such as ST elevation myocardial infarct (STEMI), clinical midterm follow-up data have highlighted cautionary findings such as increased risk of device thrombosis. The reasons for this are multifactorial and may be in part due to suboptimal implantation technique and cessation of DAPT before complete vessel healing takes place. Optimizing implantation technique and prolonged DAPT may improve clinical results.
The impact of a dedicated implantation technique on clinical outcomes may be seen in newer prospective clinical trials involving the use of newer iterations of BRS and mandating the use of accurate vessel sizing, appropriate lesion selection and preparation and aggressive scaffold postdilation supported by the use of OCT. Till then, it remains highly likely that OCT and registry based studies would once again play a fundamental role in the evaluation of the next generation of BRS and help determine the optimal implantation strategy for future use.