Data Presented and Published From the MASTER Trial of InspireMD's MGuard Stent

October 24, 2012—InspireMD, Inc. (Tel Aviv, Israel) announced the publication and presentation of study results showing that the company's MGuard embolic protection stent (EPS) was significantly superior when compared to standard bare-metal and drug-eluting stents in achieving complete ST resolution and restoring normal blood flow in 432 randomized patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI). The MGuard EPS is CE Mark approved for sale in Europe but is currently not approved by the US Food and Drug Administration and is not available for sale in the United States, advised the company.

Gregg W. Stone, MD, et al published findings from the MASTER trial online ahead of print in the Journal of the American College of Cardiology. MASTER is a prospective, randomized, multicenter evaluation of the utility of the MGuard, a polyethylene terephthalate micronet mesh-covered stent, in STEMI patients undergoing PCI.

Dr. Stone, the study's Chairman, also presented the data at the Late Breaking Trials Session at the TCT 2012: Transcatheter Cardiovascular Therapeutics conference in Miami, Florida. In the company's press release, Dr. Stone commented, “I was impressed with the performance of the MGuard EPS in the MASTER trial. Compared to standard stents, the MGuard is the first stent in a randomized trial shown to restore complete ST-segment resolution in a higher proportion of patients, a key predictor of myocardial salvage and long-term survival in STEMI patients.”

The study's background, as summarized in the Journal of the American College of Cardiology, is that 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 that is designed to trap and exclude thrombus and friable atheromatous debris to prevent distal embolization.

The MASTER investigation was conducted at 50 sites in nine countries and composed of 433 STEMI patients presenting within 12 hours of symptom onset who were undergoing PCI. These patients were randomized 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 minutes after the procedure. 

The investigators reported that baseline characteristics were well matched between the groups. The primary endpoint of postprocedure 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– 23.3%; P = .008). By core laboratory analysis, the MGuard stent compared with control stents also resulted in superior rates of TIMI 3 flow (91.7% vs 82.9%; P = .006) with comparable rates of myocardial blush grade 2 or 3 (83.9% vs 84.7%; P = .81). Mortality (0% vs 1.9%; P = .06) and major adverse cardiac events (1.8% vs 2.3%; P = .75) at 30 days were not significantly different between patients randomized to the MGuard stent and control stent, respectively.

The MASTER investigators concluded in the Journal of the American College of Cardiology that among patients with acute STEMI undergoing emergent PCI, the MGuard micronet mesh–covered stent resulted in superior rates of epicardial coronary flow and complete ST-segment resolution compared with conventional metal stents. The investigators advised that a larger randomized trial is warranted to determine whether these benefits result in reduced infarct size and/or improved clinical outcomes.