Mechanistic insights into lumen reduction after implantation of a drug-eluting bioresorbable metallic scaffold assessed with serial intracoronary imaging: from the OPTIMIS trial

Background The mechanisms behind lumen reduction after percutaneous coronary intervention with a sirolimus-eluting Magmaris bioresorbable scaffold (MgBRS) are unclear. Objectives To identify mechanisms and risk factors for lumen reduction after MgBRS implantation. Methods In the OPTIMIS-trial, patients were randomized to predilatation with a scoring balloon or a standard noncompliant balloon before MgBRS implantation. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) were performed. Patients were divided into two groups according to minimal lumen area (MLA) at 6-month follow-up: MLA less than or equal to 4 mm 2 and MLA greater than 4 mm 2 assessed with OCT. Matched-framed analysis identified MLA at the lesion site and corresponding sites postprocedure and at follow-up. Vessel injury was defined as an intrascaffold dissection flap greater than or equal to 200 µm. Logistic regression predicted MLA less than or equal to 4 mm 2 . Results Preprocedural, postprocedural, and 6-month follow-up IVUS and OCT were analyzable in 73 lesions (MLA ≤ 4 mm 2 , n = 28, and MLA > 4 mm 2 , n =45). In the MLA less than or equal to 4 mm 2 group, lumen area (7.7 ± 1.8–6.4 ± 2.6 mm 2 , P = 0.002) and vessel area (15.5 ± 3.8–14.1 ± 4.4 mm 2 ; P = 0.03) were reduced from postprocedure to follow-up, whereas lumen and vessel area did not differ significantly in the MLA less than or equal to 4 mm 2 group. Vessel injury [odds ratio (OR): 5.1, 95% confidence interval (CI): 1.4–18.8] and predilatation with a standard noncompliant balloon (OR: 4.0, 95% CI: 1.1–14.4) were independent predictors of MLA less than or equal to 4 mm 2 . Conclusion Vessel shrinkage was associated with lumen reduction at the lesion site. Vessel injury and lesion preparation with a standard noncompliant balloon were associated with MLA less than or equal to 4 mm 2 .