TCT: Mesh-covered stent shows promise for complete ST-segment resolution

MIAMI—Among patients with acute STEMI undergoing primary PCI, the MGuard micronet mesh-covered stent compared with conventional metallic stents resulted in superior rates of epicardial coronary flow and complete ST-segment resolution (STR), according to the MASTER trial presented Oct. 24 at the Transcatheter Cardiovascular Therapeutics (TCT) conference.

The study was simultaneously published Nov. 6 in the Journal of the American College of Cardiology (JACC).

The MASTER trial tested a new stent, the MGuard (InspireMD), which is covered with a polyethylene terephthalate (PET) micronet mesh that seeks to trap or exclude downstream embolization by holding plaque or thrombus in place against the wall of the blocked artery. “This is an embolic protection device, more than a stent,” explained co-investigator Sigmund Silber, MD, PhD, of Heart Center at the ISAR in Munich, who presented the study during a press conference.

“STEMI patients have a lot of thrombus in the artery, and sometimes the artery is occluded or very highly narrowed,” explained Silber. “If you push a balloon through this thrombus, you have a risk of dislodging plaque, and then there is nothing you can do about it. No intervention can heal this, so you have to prevent it.”

Between July 22, 2011 and May 29, 2012, 433 STEMI patients were enrolled and randomized at 50 sites in nine countries. The median age of the patients was 59; 24 percent of them were female. In the study, 204 patients received the MGuard stent and 206 patients received either a drug-eluting stent (DES) or bare-metal stent (BMS) in the control group. Follow-up took place at 30 days, six months and one year.

The primary endpoint was the rate of complete (>70 percent) STR at 60 to 90 minutes following the procedure.

In the group of patients with the mesh-covered stent, the rate of compete STR was 57.8 percent; in the control group, the rate was 44.7 percent. In both groups, there were approximately 17 percent of patients who had no STR, reported Silber.

The physician panelists discussed what difference between the two arms would be enough, and they concluded that this number may be somewhat ambiguous and may be different for different patients. However, Roxana Mehran, MD, of Mount Sinai Hospital in New York City, concluded: “I’ll take 13 percent,” which was the difference found in this trial.

In the core lab analysis, the MGuard stent compared with control stents also resulted in superior rates of blush grade 2 or 3 (83.9 vs. 84.7 percent).

However, mortality (0 vs. 1.9 percent) and major adverse cardiac events (1.8 vs. 2.3 percent) at 30 days were not significantly different between patients randomized to the MGuard stent and control stent, respectively. Silber noted that while zero patients died in the MGuard group and four patients died in the control, the study was underpowered to look at mortality.

Long-term follow-up is ongoing, wrote the study authors in JACC, and “is essential to examine the late results with MGuard stent after primary PCI in STEMI.” At TCT.12, Silber noted that 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 (MASTER II).

The MASTER trial was funded by InspireMD.