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MAGSTEMI: Mixed results for magnesium-based bioresorbable scaffold vs. SES

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SAN FRANCISCO — Magnesium-based bioresorbable scaffolds resulted in a greater capacity of vasomotor response to pharmacological agents compared with sirolimus-eluting stents among patients with STEMI, according to 1-year follow-up data from the MAGSTEMI trial presented at TCT 2019.

Conversely, patients assigned magnesium-based bioresorbable scaffolds (Magmaris, Biotronik) had a higher rate of target lesion revascularization and lower angiographic efficacy without concerns about thrombotic safety compared with those assigned SES (Orsiro, Biotronik), according to the study, which was simultaneously published in Circulation.

Manel Sabaté , MD, PhD, chief of the interventional cardiology department at the Clinic University Hospital in Barcelona, Spain, and associate professor at the Central University of Barcelona, and colleagues analyzed data from 150 patients with STEMI who were undergoing primary PCI. Patients were assigned a magnesium-based bioresorbable scaffold (n = 74; mean age, 59 years; 85% men) or an SES (n = 76; mean age, 59 years; 93% men).

“Both stents have the same antiproliferative drug, polymer, passive coating and drug elution kinetics, whereas the strut thickness of the Orsiro is 60 µm to 80 µm, the one of the Magmaris is 150 µm,” Sabaté and colleagues wrote.

The technique used to implant the SES was left to the operator’s discretion, whereas a dedicated implantation technique was used for magnesium-based bioresorbable scaffold implantation. The use of glycoprotein IIb/IIIa and periprocedural anticoagulation was also left to the operator’s discretion. Both groups were prescribed dual antiplatelet therapy for 1 year.

Follow-up was conducted for up to 5 years after the index procedure, which included telephone contacts or clinical visits to collect information on hospitalizations, CV drug use, clinical events and noninvasive or invasive diagnostic tests at 30 days, 6 months, 12 months and annually thereafter. Angiographic follow-up was performed at 12 months to assess the primary endpoint, defined as in-stent/in-scaffold vasodilatory response of at least 3% after intracoronary nitroglycerin injection. Secondary endpoints included procedure success, device success, patient-oriented and device-oriented composite endpoints and their individual components, and stent/scaffold thrombosis.

A substudy was also performed in 69 patients to assess endothelium-dependent vasomotor response of the target segment, which was assessed during angiographic follow-up at 12 months. Comparisons made between both groups included changes in mean luminal diameter of the proximal, and distal and in-device segments from baseline to the maximum dose of acetylcholine.

The primary endpoint at 1 year was higher among patients assigned magnesium-based bioresorbable scaffolds vs. those assigned SES (56.5% vs. 33.8%; P = .01). In contrast, patients in the SES group had significantly lower in-stent (0.06 mm vs. 0.61 mm; difference = –0.55; 95% CI, –0.69 to –0.41) and in-segment late lumen loss (0.02 mm vs. 0.39 mm; difference = –0.37; 95% CI, –0.5 to –0.24) compared with patients assigned magnesium-based bioresorbable scaffolds.

The magnesium-based bioresorbable scaffold arm had a higher rate of the device-oriented composite endpoint vs. the SES arm, which was driven by an increased rate of ischemia-driven TLR (16.2% vs. 5.2%: P = .03). The magnesium-based bioresorbable scaffold and SES groups had similar rates of definite thrombosis (1.4% vs. 2.6%, respectively; difference = 1.2; 95% CI, –3.2 to 5.7).

Patients assigned magnesium-based bioresorbable scaffolds had a more pronounced vasoconstrictive response to a maximum dose of acetylcholine compared with those assigned SES (–8.3% vs. –2.4%; P = .003).

“Current magnesium-based bioresorbable scaffold generation was associated with a lower angiographic efficacy (ie, higher late lumen loss), higher rate of target lesion revascularization, without safety concerns in this thrombogenic setting,” Sabaté and colleagues wrote. “Further iterations of the device with longer scaffolding time and higher radial force may help to resolve this drawback.” – by Darlene Dobkowski

References:

Sabate M. High-Impact Clinical Research II: High-Risk Disease and Novel Therapies. Presented at: TCT Scientific Symposium; Sept. 25-29, 2019; San Francisco.

Sabate M, et al. Circulation. 2019;doi:10.1161/CIRCULATIONAHA.119.043467.

Disclosures: The trial was funded by the Spanish Heart Foundation. Sabaté reports he is a consultant for Abbott Vascular and iVascular. Please see the study for all other authors’ relevant financial disclosures.