The Magmaris magnesium (Mg)-based sirolimus-eluting bioresorbable scaffold (BRS) demonstrates a favorable safety profile in ST-segment elevation myocardial infarction (STEMI) patients at 5 years, the MAGSTEMI study shows. As in 1-year results, the target vessel revascularization (TLR) rates continued to trend higher for Magmaris (Biotronik) versus a permanent metallic stent, yet the researchers noted that this was primarily related to early events in the resorption period. The findings were reported Monday online in a JACC: Cardiovascular Interventions research letter, led by Manel Sabaté, MD, from Hospital Clinic Barcelona, Spain. They are the first long-term safety results for the Mg BRS after complete scaffold resorption in STEMI, the researchers said. BRS are designed to provide early mechanical support following percutaneous coronary intervention (PCI) and disappear at a later stage, in a bid to avoid long-term complications related to permanent stents, the researchers noted. The 150-patient MAGSTEMI (Magnesium-Based Bioresorbable Scaffold and Vasomotor Function in Patients With Acute ST-Segment Elevation Myocardial Infarction) trial randomized patients 1:1 to Magmaris or permanent stent. It showed Biotronik's second-generation Mg-based sirolimus-eluting stent (SES) to have a superior vasomotor response at 1-year follow-up versus a permanent metallic SES. Magmaris carried a higher 1-year risk of TLR, "likely because of scaffold collapse of the platform, which was identified as the main mechanism of restenosis," the researchers wrote. In the current analysis, rates of the 5-year device-orientated clinical endpoint — a composite of cardiac death, target vessel myocardial infarction, or ischemia-driven TLR — were not significantly different between the two groups (9.2% in permanent BRS vs 17.6% in the Magmaris group; P = 0.12). Similarly, there was no significant difference in a patient-oriented composite endpoint, which encompassed all-cause death, any myocardial infarction, or any revascularization (23.7% in permanent BRS vs 27% in the Magmaris group; P = 0.55). There was also no difference in individual endpoints between the arms, including cardiac death (1.3% in permanent BRS vs 1.4% in the Magmaris group; P = 0.98), any myocardial infarction (7.9% vs 4.1%, respectively; P = 0.33) and definite or probable device thrombosis (3.4% vs 1.4%, respectively; P = 0.33), while 5-year cumulative incidence of dual antiplatelet therapy was similarly low in both groups (7.4% in permanent BRS vs 5.8% in Magmaris; P = 0.76). Higher TLR rate for Mg BRS Despite compatible endpoints with permanent SES, the second-generation Mg BRS, TLR rates continued to be higher in the Magmaris group at 5 years (6.6% VS 16.2%; P = 0.059). Target vessel revascularization (TVR) was also higher for the Magmaris group (10.5% vs 20.3%; P = 0.09). However, "landmark analysis of TLR did not show any difference between the 2 groups beyond 1 year," the researchers wrote, stressing that no TLR occurred beyond 1 year and no scaffold thrombosis occurred after index hospitalization. "Conceptually, STEMI culprit lesions can be the proper target for bioresorbable technology, as they are typically composed of soft material, allowing proper vessel preparation. On the contrary, the implantation of a metallic stent in this context is associated with a 1% to 2% risk for subsequent events in the long term." The researchers concluded that the second-generation Magmaris device demonstrated safety up to 5 years. They added that a third generation of the Mg BRS, named Freesolve, is aimed at solving the issue of early high restenosis rates via improved mechanical properties. "This new iteration has an increased radial force compared with its predecessor," the authors noted. "This has been achieved despite a reduction of strut thickness." The device has been through first-in-human testing in the BIOMAG-I trial and is undergoing further study in the BIOMAG-II randomized controlled trial. Source: Sabaté s, Alfonso F, Gómez-Lara J, et al. Magnesium-Based Resorbable Scaffold vs Sirolimus-Eluting Stent in STEMI Patients: 5-Year Results of the MAGSTEMI Trial. JACC: Cardiovasc Interv 2025;doi:10.1016/j.jcin.2025.04.048. Image Credit: Magmaris BRS – biotronik.com