Safety and Efficacy Study of MGuard Stent After a Heart Attack - MASTER (Mesh-Covered Stent)


The goal of the trial was to evaluate treatment of a thin-strut stent with micronet covering compared with a commercially available stent among patients with ST-segment elevation myocardial infarction (STEMI).


MGuard stent will prevent distal embolization, and thus improve myocardial reperfusion.

Study Design

  • Randomized
  • Parallel
  • Stratified

Patient Populations:

  • Patients ≥18 years of age with STEMI ≤12 hours in duration
  • De novo lesion <33 mm in length between 3 and 4 mm in diameter

    Number of enrollees: 433
    Duration of follow-up: 30 days
    Mean patient age: 60 years
    Percentage female: 25%


  • Left bundle branch block, paced rhythm, or other electrocardiogram abnormality precluding assessment of ST-segments
  • PCI within the last 6 months
  • Prior coronary artery bypass grafting
  • Bleeding abnormality or use of warfarin
  • Contraindication to any study medication or device
  • Chronic kidney disease
  • Left ventricular ejection fraction ≤20%
  • Cardiogenic shock or cardiopulmonary resuscitation
  • Life expectancy <1 year
  • Left main stenosis ≥50%
  • Ostial or bifurcation lesion
  • Target vessel with excessive calcification, tortuosity, or angulation
  • >50% stenosis proximal or distal to the culprit lesion
  • Prior stent proximal to or 10 mm distal to target lesion

Primary Endpoints:

  • Rate of complete ST-resolution (≥70%) 60-90 minutes post-procedure

Secondary Endpoints:

  • TIMI 3 flow
  • Myocardial blush grade 2/3
  • Mortality at 30 days
  • Reinfarction and stent thrombosis at 30 days
  • Major adverse cardiac events at 30 days

Drug/Procedures Used:

Patients with STEMI were randomized to a thin-strut stent with micronet covering (MGuard; n = 217) versus a commercially available bare-metal or drug-eluting stent (n = 216).

Prior to percutaneous coronary intervention (PCI), patients received aspirin and a loading dose of an adenosine diphosphate receptor antagonist (clopidogrel, prasugrel, or ticagrelor). During PCI, patients received unfractionated heparin plus a glycoprotein IIb/IIIa inhibitor or bivalirudin monotherapy. Low molecular weight heparin, fondaparinux, or intracoronary glycoprotein IIb/IIIa inhibitor was not permitted.

Aspiration thrombectomy and/or pre-dilatation prior to stent implantation was left to operator discretion.

Principal Findings:

Overall, 433 patients were randomized. The mean age was 60 years, 25% were women, 12% had diabetes, mean body mass index was 27 kg/m2, aspiration thrombectomy was performed in 66%, and pre-dilatation was performed in 50%.

Device success was 96% in the MGuard group versus 99% in the control group (p = 0.03).

The primary outcome, complete ST-resolution 60-90 minutes post-procedure, occurred in 57.8% of the micronet-covered stent group versus 44.7% of the control group (p = 0.008).

The following individual outcomes were reported as MGuard versus control:
- TIMI 3 flow: 91.7% versus 82.9% (p = 0.006)
- Myocardial blush grade 2/3: 83.9% versus 84.7% (p = 0.81)
- Mortality at 30 days: 0 versus 1.9% (p = 0.06)
- Reinfarction and stent thrombosis at 30 days: 1.4% versus 0.9% (p = 1.0)
- Major adverse cardiac events at 30 days: 1.8% versus 2.3% (p = 0.75)


Among patients with STEMI treated with aspiration thrombectomy, the use of the novel micronet-covered stent was feasible. This device improved one marker of myocardial reperfusion: complete ST-resolution (primary outcome); however, it did not improve myocardial blush grade 2/3 (secondary outcome). Although it was not necessarily designed to improve epicardial coronary flow post-PCI compared with a conventional stent, TIMI flow 3 was also improved in the micronet-covered stent group. Clinical outcomes appeared similar between the treatment groups. It is unknown how this device would have performed without the frequent use of aspiration thrombectomy.


Stone GW, Abizaid A, Silber S, et al. Prospective, randomized, multicenter evaluation of a polyethylene terephthalate micronet mesh-covered stent (MGuard) in ST-segment elevation myocardial infarction: The MASTER trial. J Am Coll Cardiol 2012;Oct 24:[Epub ahead of print].

Presented by Dr. Gregg Stone at the Transcatheter Cardiovascular Therapeutics meeting (TCT 2012), Miami, FL, October 24, 2012.

Keywords: Myocardial Infarction, Follow-Up Studies, Drug-Eluting Stents, Heparin, Low-Molecular-Weight, Dilatation, Purinergic P2Y Receptor Antagonists, Percutaneous Coronary Intervention, Body Mass Index, Thrombectomy, Thrombosis, Diabetes Mellitus, Myocardial Reperfusion

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