This included the temporary suspension of the MASTER II trial and the addition of a new step during the manufacturing process so-called thermoforming in which the balloon-shaping process forms “shoulders,” which are intended to provide additional securement of the stent to the delivery system. 12 Similarly, stent dislodgement occurred in six of 155 cases with the MGuard Prime stent (3.87%) at the IDE-MGuard for acute ST-elevation reperfusion II (MASTER II) trial, 14 which led the manufacturer in 2014 to a voluntary field safety corrective action. Stent dislodgement was reported in two of 217 cases (0.9%) of the prospective, randomized, multicenter evaluation of a polyethylene terephthalate micronet mesh–covered stent (MGuard) in ST-segment elevation myocardial infarction (MASTER) trial. By contrast, no cases of net detachment from the stent were seen. 13įrom January 2011 to April 2014, the manufacturer received 54 complaints of stent dislodgement from the delivery system, most occurring with the MGuard Prime stent. Similarly, a recent single-center experience reported 1.8% of cases in which the stent could not reach the lesion. 12 Of note, all nine cases occurred with the stainless steel platform. In a recent trial, the MGuard stent was unable to reach or cross the culprit lesion in nine of 217 cases (4.1%). Crossing profile is slightly higher than newer-generation bare metal stents (1.1–1.3 mm for the stainless steel platform and 1.0–1.2 mm for the cobalt chromium platform), which together with the close-cell design may impair the deliverability. The MGuard stent is compatible with 0.014 in guide wires and 6 Fg guiding catheters. Guiding catheter, deliverability, and stent dislodgement The purpose of this review is to summarize all the relevant literature available about the use of this device. The MGuard stent is a novel bare metal stent with a porous net attached to its outer surface that has been designed to trap thrombus debris reducing distal embolization, while pores allow normal endothelization of the stent through the membrane. Importantly, the barrier created by the membrane was related to delayed endothelization of the stent and also to side branch occlusion, which could explain the increased rate of myocardial infarction. 8 However, covered stents, compared with bare metal stents, were associated with an increased risk of myocardial infarction, thus prohibiting their use in this scenario. The concept of a stent covered with a membrane attached to its outer surface (to create a mechanical barrier to prevent thrombus fragmentation and filtration through the struts) has also been tested previously. 5 Similarly, catheter-based thrombus aspiration has been associated with controversial results although early single-center studies suggested a potential benefit, recent trials have shown no reductions in infarct size or mortality. 3 Distal protection devices failed to show reductions in infarct size or mortality in patients undergoing primary PCI, 4 although they seem to improve angiographic and clinical outcomes in PCI of degenerated SVG. Thus, several pharmacological and technical strategies have been tested to minimize the distal embolization risk. Prevention of embolization rather than treatment should be the way forward as treatment is unlikely to succeed if no reflow is established. Inadequate myocardial reperfusion may occur in up to 50% of cases despite the use of optimal evidence-based coronary revascularization and is associated with a worse in-hospital and long-term prognosis. 1 Patients with acute coronary syndromes and those undergoing PCI of saphenous vein graphs (SVGs) are at highest risk of distal embolization, which frequently occurs after stent implantation due to thrombus fragmentation and protrusion by the stent struts. Atheromatous and thrombotic embolization during percutaneous coronary intervention (PCI) is a feared complication that may cause impaired myocardial reperfusion even with a patent epicardial vessel.
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