Prospective, Randomized, Multicenter Evaluation of a Polyethylene Terephthalate Micronet Mesh-Covered Stent (MGuard) in ST-Segment Elevation Myocardial Infarction: The MASTER Trial.

OBJECTIVES: This study sought to evaluate the potential utility of a novel polyethylene terephthalate micronet mesh-covered stent (MGuard) in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI).

BACKGROUND: Suboptimal myocardial reperfusion after PCI in STEMI is common and results in increased infarct size and mortality. The MGuard is a novel thin-strut metal stent with a polyethylene terephthalate micronet covering designed to trap and exclude thrombus and friable atheromatous debris to prevent distal embolization.

METHODS: A total of 433 patients with STEMI presenting within 12 h of symptom onset undergoing PCI were randomized at 50 sites in 9 countries to the MGuard (n = 217) or commercially available bare metal or drug-eluting stents (n = 216). The primary endpoint was the rate of complete (≥70%) ST-segment resolution measured 60 to 90 min post-procedure.

RESULTS: Baseline characteristics were well matched between the groups. The primary endpoint of post-procedure complete ST-segment resolution was significantly improved in patients randomized to the MGuard stent compared with control patients (57.8% vs. 44.7%; difference: 13.2%; 95% confidence interval: 3.1% to 23.3%; p = 0.008). By core laboratory analysis, the MGuard stent compared with control stents also resulted in superior rates of Thrombolysis In Myocardial Infarction 3 flow (91.7% vs. 82.9%, p = 0.006) with comparable rates of myocardial blush grade 2 or 3 (83.9% vs. 84.7%, p = 0.81). Mortality (0% vs. 1.9%, p = 0.06) and major adverse cardiac events (1.8% vs. 2.3%, p = 0.75) at 30 days were not significantly different between patients randomized to the MGuard stent and control stent, respectively.

CONCLUSIONS: Among patients with acute STEMI undergoing emergent PCI, the MGuard micronet mesh-covered stent compared with conventional metal stents resulted in superior rates of epicardial coronary flow and complete ST-segment resolution. A larger randomized trial is warranted to determine whether these benefits result in reduced infarct size and/or improved clinical outcomes. (Safety and Efficacy Study of MGuard Stent After a Heart Attack [MASTER]; NCT01368471).