Mesh-Covered Stent Shines in MASTER Trial

MIAMI BEACH, FLA.—In STEMI patients undergoing emergent PCI, a new stent increases the rate of complete ST-segment resolution compared with conventional BMS and DES. Findings from the MASTER study were presented in a late-breaking session at TCT 2012 and simultaneously published online in the Journal of the American College of Cardiology.

“The MGuard Embolic Protection Stent [Inspire MD] is a novel thin-strut metal stent with a PET micronet covering designed to trap and exclude thrombus and friable atheromatous debris [in order] to prevent distal embolization,” said lead investigator Gregg W. Stone, MD, of Columbia University Medical Center, New York.

For the MASTER trial, researchers enrolled 433 STEMI patients at 50 sites in 9 countries who presented within 12 hours of symptom onset. Patients were randomly assigned to receive commercially available stents (n=216; 60% BMS; 40% DES) or MGuard (n = 217). Baseline characteristics were well balanced between the two groups.

Device success (< 50% final residual stenosis using only the randomized stent) was lower with MGuard at 95.9% vs. 99.1% (P=.03). MGuard patients were more likely to attain TIMI flow grade 3 than controls (91.7% vs. 82.9%; P=.006), though rates of myocardial blush grade 2 or 3 (MGuard, 83.9% vs. control, 84.7%; P=.81) and intraprocedural thrombotic events (MGuard, 21.7% vs. 22.3%; P=.87) were similar between study arms.

Complete ST-segment resolution, the primary endpoint, occurred more often with the novel device (see Figure). The benefit was consistent across numerous prespecified subgroups. In addition, an MRI substudy (n=59) at 3 to 5 days showed similar median values for infarct mass with MGuard vs. standard stents (13.3% vs. 16.6% of total LV mass; P=.48), microvascular obstruction (0.4% vs. 0.8% of total LV mass; P=.39) and other measures.

At 30 days, clinical events were rare and differences did not reach statistical significance. Cardiac mortality, however, occurred in 1.9% of the standard stent group, but none of the MGuard group (P=.06).  None of the 211 patients with complete ST-segment resolution died, compared with 2% of the 198 patients with partial or absent resolution (P=.05).

 “A larger randomized trial is warranted to verify these findings and determine whether these benefits result in reduced infarct size and/or improved clinical outcomes,” Stone concluded, reporting that the MASTER II trial is currently under development.

 “Distal embolization is a bad thing,” Jose P.S. Henriques, MD, PhD,  of the Academic Medical Center in Amsterdam, the Netherlands, commented after Stone’s presentation. “Although a larger trial is required, this stent really seems to do what it is meant to do.”