Coronary Artery Healing Process after Bioresorbable Scaffold in Patients with Non-ST-Segment Elevation Myocardial Infarction: Rationale, Design, and Methodology of the HONEST Study

Background: Bioresorbable scaffolds (BRSs) is a relatively new approach in treating coronary artery stenosis. The initial results of the first commercially available scaffolds consisting of a backbone of poly-L-lactide raised safety concerns related to delayed resorption and healing. The magnesium alloy-based scaffold degrades via bio-corrosion within months, whereas it often takes several years for polymer scaffolds to degrade. The aim of the study was to assess the healing stage by optical coherence tomography (OCT) after 6 months in patients with non-ST-segment elevation myocardial infarct (NSTEMI) randomized to OCT or angiography-guided percutaneous coronary intervention with implantation of a magnesium sirolimus-eluting Magmaris scaffold (Magmaris; Biotronik, Bulach, Switzerland). Methods: We analyzed the healing process by comparing OCT at baseline and after 6 months. Five stages of healing were defined with stage 1 being the least healed and stage 5 demonstrating complete resorption and healing with no visible scaffold/remnant. The primary end point is a calculated healing score that is based on 5 subtypes of healing stage: (1) malapposed, (2) uncovered with no detection of smooth surface tissue on top of struts or remnants, (3) covered protruding, (4) covered embedded, and (5) complete healing with a smooth neointimal surface and no sign of struts or visible remnants assessed by OCT 6 months after the index procedure. Results: The impact of OCT-guided compared to angiography-guided scaffold implantation will be illuminated. Conclusion: The present study will provide new information on midterm healing properties of the magnesium BRS in patients with NSTEMI.