Original title: The MASTER Trial – Prospective, Randomized, Multicenter Evaluation of a Polyethylene Terephthalate Micronet Mesh–Covered Stent (MGuard) in ST-Segment Elevation Myocardial Infarction. Reference: Gregg W. Stone et. al. J Am Coll Cardiol 2012; 60: 1975-1984

Primary angioplasty has proven effective in restoring epicardial flow but myocardial perfusion is often suboptimal. One of the main mechanisms is distal embolization of the thrombus and friable detritus. Many drugs and devices have attempted to improve this problem but with conflicting results.

The MGuard stent (InspireMD, Tel Aviv, Israel) is a metal stent with a micro articulated mesh designed to exclude friable material and prevent embolization.

This study compared the efficacy of the MGuard stent versus a control stent, (BARE or DES at the discretion of the surgeon), in patients who had acute myocardial infarction with ST-segment elevation undergoing primary angioplasty. The primary end point was ST segment resolution, (> 70% reduction compared with baseline).

433 patients were randomized, (217 MGuards versus 216 control stents). Thrombus aspiration was performed in 2 out of 3 patients and balloon pre dilation, (mean 2 mm), to 50%. ST-segment resolution in the MGuard group was higher compared to the control stent group, (57.8% versus 44.7% respectively, p = 0.008), as was the rate of TIMI III final, (91.7% versus 82.9% respectively, p = 0.006). The MGuard group showed a trend toward lower cardiac mortality at 30 days, (0 versus 1.9%, p = 0.06). There were no significant differences between the groups in the rate of reinfarction, instent thrombosis or vessel revascularization motivated by ischemia.

The MGuard stent was unable to cross the lesion in 9 patients (4.1%) and 2 of these patients suffered distal embolization without clinical consequences thereof.

Conclusion 

The MGuard stenting was associated with a higher TIMI III flow and complete ST-segment resolution in primary angioplasty.

Editorial Comment:

This study does not have enough power to show clinical results or conclusions of subgroups, nevertheless the MGuard stent seems a promising tool in primary angioplasty. Note the tortuosity and calcification of the lesion as the MGuard does not have a great seaworthiness. 1:1 pre-dilation would remove the potential benefit in preventing embolization.

Dr. Francisco Ortega.