Polymer-free Sirolimus Eluting Stent: Real-world Investigation of Safety and Outcomes

Overview

POLARIS is a prospective, single-centre, single-arm observational pilot registry evaluating the real-world safety and efficacy of the Focus np (Abluminus np, Concept Medical, Tampa, FL, USA) polymer-free sirolimus-eluting stent in consecutive adult patients undergoing percutaneous coronary intervention (PCI). The primary endpoint is target lesion failure (TLF) at 12 months, defined per Academic Research Consortium-2 (ARC-2) criteria as the device-oriented composite of cardiac death, target vessel myocardial infarction, and clinically indicated target lesion revascularisation. Patients treated since January 2021 will be retrospectively identified and prospectively consented, with follow-up through 5 years. The registry will provide the first Western clinical evidence on this CE-marked device and serve as a template for a future national Swiss multicentre registry.

BACKGROUND. Newer-generation drug-eluting stents (DES) remain associated with late stent-related adverse events at approximately 2% per year, driven by neoatherosclerosis, delayed endothelial healing, and chronic inflammation attributable to permanent polymer coatings. Polymer-free DES were developed to remove this substrate. The polymer-free sirolimus-based submicron carrier-eluting stent Focus np (Abluminus np, Concept Medical, Tampa, FL, USA) (after: study device) is a novel polymer-free sirolimus-eluting stent built on a thin-strut (73 micrometres) cobalt-chromium platform, with drug delivery via biodegradable phospholipid submicron carriers (200-300 nm) confined to the abluminal surface, and a proprietary fusion coating extending sirolimus up to 5 mm beyond the stent edges. The device received CE marking on 24 January 2020. Only limited non-randomized Indian clinical data exist; no Western clinical data have been published. OBJECTIVES. Primary: to evaluate device-oriented safety and efficacy (TLF at 12 months) of the stent in an all-comer population undergoing PCI at Geneva University Hospitals. Secondary: TLF at 2 and 5 years; individual components of TLF (cardiac death, target vessel MI, clinically indicated target lesion revascularisation) at 30 days, 12 months, 2 years, and 5 years; patient-oriented composite endpoint (all-cause death, any MI, any revascularisation); stent thrombosis (definite / probable, ARC-2, with temporal classification); target vessel failure; major bleeding (BARC 3 or 5); all-cause mortality; and late lumen loss when angiographic follow-up is available. DESIGN. Prospective, single-centre, single-arm observational registry (Category A research with human subjects per the Swiss Human Research Act). Hybrid enrolment: retrospective identification from January 2021, prospective consent, and prospective follow-up at 30 days, 12 months, 2 years, and 5 years via medical records and telephone interview. POPULATION. All consecutive adult patients (\>= 18 years) treated with at least one study device stent at Geneva University Hospitals since January 2021, with an indication for PCI according to current European or American guidelines, able to provide written informed consent, and with sufficient knowledge of French, German, English, or Italian. STATISTICS. Exploratory, descriptive analysis. Binary endpoints with Clopper-Pearson 95% confidence intervals; time-to-event analysis by Kaplan-Meier with Greenwood 95% CIs. Pre-specified exploratory subgroup analyses (sex, clinical presentation, diabetes, age, lesion complexity, stent length) presented as forest plots without between-group p-values. Sensitivity analyses include per-protocol, complete-case, landmark (30 days to 12 months), Fine-Gray competing-risk, and tipping point analyses. Analyses in Python (lifelines, pandas, scipy, statsmodels). Reporting follows STROBE.