The IRONMAN-II trial was a prospective, multicenter, single-blinded, noninferiority randomized study conducted across 36 centers in China. Patients with myocardial ischemia and 1 or 2 de novo target coronary lesions were eligible and randomly assigned (1:1) to receive a thin-strut sirolimus-eluting iron bioresorbable scaffold (IBS) or a cobalt chromium everolimus-eluting stent (CoCr-EES). A total of 518 patients were randomized (259 per group) between March 10 and December 13, 2022. Optical coherence tomography (OCT) was performed in the first 25 participant pairs. The study was published in the Journal of American College of Cardiology.

The primary endpoint was 2-year angiographic in-segment late lumen loss (LLL). At 2 years, mean 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_noninferiority=0.03). Mean quantitative flow ratio was 0.90 (0.13) versus 0.92 (0.09) (difference −0.02; 95% CI −0.04 to 0; P_noninferiority=0.05). OCT-derived mean flow area was 6.92 (3.48) mm² versus 6.64 (2.44) mm² (difference 0.27; 95% CI −0.09 to 0.63; P_noninferiority<0.0001).

Two-year target lesion failure occurred in 7.4% versus 5.4% (HR 1.37; 95% CI 0.69–2.73; P=0.37). No scaffold thrombosis occurred with IBS; one stent thrombosis occurred with CoCr-EES.

The sirolimus-eluting IBS met noninferiority criteria for angiographic and physiologic endpoints at 2 years. Longer-term follow-up is required to determine potential late effects after scaffold resorption.