Sirolimus-eluting iron bioresorbable scaffold shows higher late lumen loss than everolimus-eluting stents in coronary artery disease patients.

BACKGROUND: The novel thin-strut sirolimus-eluting iron bioresorbable scaffold (IBS) demonstrated safety and efficacy in a nonrandomized first-in-human study. OBJECTIVES: The objective of this study was to compare the IBS with contemporary metallic cobalt chromium everolimus-eluting stents (CoCr-EES) in patients with coronary artery disease. METHODS: IRONMAN-II was a prospective, multicenter, single-blinded, noninferiority randomized trial across 36 centers in China. Eligible patients had myocardial ischemia and 1 or 2 de novo target lesions. Patients were randomly assigned (1:1) to IBS or CoCr-EES, with allocation masked. Optical coherence tomography (OCT) was performed in the first 25 participant pairs. Clinical follow-up was scheduled at 1, 6, and 12 months, and annually to 5 years, with angiographic and OCT follow-up at 2 years. The primary endpoint was 2-year angiographic in-segment late lumen loss (LLL). Powered secondary endpoints included target vessel quantitative flow ratio (QFR) and OCT-derived cross-sectional mean flow area. Other secondary endpoints included target lesion failure (cardiac death, target vessel myocardial infarction [MI], or ischemia-driven target vessel revascularization), the patient-oriented composite endpoint (all-cause death, MI, or any revascularization), their individual components, and device thrombosis. RESULTS: Between March 10 and December 13, 2022, 518 patients were randomized to IBS (n = 259) or CoCr-EES (n = 259). At 2 years, lesion-level in-segment LLL was 0.28 (0.52) mm with IBS and 0.23 (0.43) mm with CoCr-EES (difference: 0.08 mm; 95% CI: -0.02 to 0.18; P = 0.03). Mean QFR was 0.90 (0.13) with IBS and 0.92 (0.09) with CoCr-EES (difference: -0.02; 95% CI: -0.04 to 0; P = 0.05). Mean OCT flow area was 6.92 (3.48) mm with IBS and 6.64 (2.44) mm with CoCr-EES (difference: 0.27; 95% CI: -0.09 to 0.63; P < 0.0001). Two-year target lesion failure occurred in 7.4% of IBS patients and 5.4% of CoCr-EES patients (HR: 1.37; 95% CI: 0.69-2.73; P = 0.37). No significant between-group differences in the rates of patient-oriented composite endpoint, death, or MI were present between the 2 groups. No scaffold thromboses occurred in the IBS group, whereas 1 stent thrombosis occurred with CoCr-EES. Binary restenosis and revascularization rates were higher with IBS, however, most such events were non-ischemia-driven. CONCLUSIONS: In IRONMAN-II, the sirolimus-eluting IBS was noninferior to CoCr-EES for 2-year in-segment LLL, QFR, and OCT-derived flow area. Clinical event rates were also comparable between groups although non-ischemia-driven revascularization rates were higher after IBS. Longer-term follow-up is necessary to demonstrate whether late benefits are realized after complete IBS resorption. (A Clinical Investigation to Evaluate the Safety and Efficacy of IBS in Patients With Coronary Artery Disease; NCT05206084).