MGuard Mesh-Covered Stent for Treatment of ST-Segment Elevation Myocardial Infarction with High Thrombus Burden Despite Manual Aspiration

Coronary No-Reflow after Primary Percutaneous Coronary Intervention-Current Knowledge on Pathophysiology, Diagnosis, Clinical Impact and Therapy

Coronary no-reflow (CNR) is a frequent phenomenon that develops in patients with ST-segment elevation myocardial infarction (STEMI) following reperfusion therapy. CNR is highly dynamic, develops gradually (over hours) and persists for days to weeks after reperfusion. Microvascular obstruction (MVO) developing as a consequence of myocardial ischemia, distal embolization and reperfusion-related injury is the main pathophysiological mechanism of CNR. The frequency of CNR or MVO after primary PCI differs widely depending on the sensitivity of the tools used for diagnosis and timing of examination. Coronary angiography is readily available and most convenient to diagnose CNR but it is highly conservative and underestimates the true frequency of CNR. Cardiac magnetic resonance (CMR) imaging is the most sensitive method to diagnose MVO and CNR that provides information on the presence, localization and extent of MVO. CMR imaging detects intramyocardial hemorrhage and accurately estimates the infarct size. MVO and CNR markedly negate the benefits of reperfusion therapy and contribute to poor clinical outcomes including adverse remodeling of left ventricle, worsening or new congestive heart failure and reduced survival. Despite extensive research and the use of therapies that target almost all known pathophysiological mechanisms of CNR, no therapy has been found that prevents or reverses CNR and provides consistent clinical benefit in patients with STEMI undergoing reperfusion. Currently, the prevention or alleviation of MVO and CNR remain unmet goals in the therapy of STEMI that continue to be under intense research.

Aspiration Thrombectomy in Patients with Acute Myocardial Infarction-5-Year Analysis Based on a Large National Registry (ORPKI)

Blood flow restoration after primary percutaneous coronary intervention (pPCI) in patients with acute myocardial infarction (AMI) may not always be achieved and could be complicated by the no-reflow phenomenon (NRP). The aim of the current study was to assess the frequency of thrombus aspirations (TAs) and NRPs in patients with AMI and treated with pPCI based on the data collected during a 5-year period in the national ORPKI registry, as well as the frequency of periprocedural strokes and predictors of TA and NRP. This retrospective analysis was performed on prospectively collected data gathered in the Polish National Registry of Percutaneous Coronary Interventions (ORPKI), which covered the period between January 2014 and December 2018, and included 200,991 patients treated due to AMI out of 535,857 patients treated using PCI. Among them, 16,777 patients underwent TA. TA was mainly used in the STEMI subgroup of 14,207 patients (84.8%). The frequency of NRP among AMI patients in the thrombectomy group was 2.75% and in the non-thrombectomy group 0.82%. Predictors of TA and NRP were also assessed using multivariate analysis. The percentage of patients treated with pPCI and with PCI alone increased significantly in all of the three selected groups of patients from 88.7% to 94.3% in the AMI group (p < 0.001), from 82.3% to 90.3% in the STEMI subgroup (p < 0.001), and from 96.3% to 98.2% in the NSTEMI subgroup (p < 0.001) during the analysed period. NRP occurred more often in the thrombectomy group for the NSTEMI (0.58% vs. 3.07%, p < 0.05) and STEMI (1.06% vs. 2.69%, p < 0.05) subgroups. Periprocedural stroke occurred more often in the thrombectomy group in comparison to the non-thrombectomy group with AMI (0.03% vs. 0.01%, p < 0.05) and the NSTEMI (0.16% vs. 0.02%, p < 0.05). In conclusion, the frequency of TA has been experiencing a steady decline in recent years, regardless of AMI type, among patients treated with pPCI.

Mechanical strategies to enhance myocardial salvage during primary percutaneous coronary intervention in patients with STEMI

Primary percutaneous coronary intervention (PPCI) has become the mainstay of reperfusion therapy in patients with ST-segment elevation myocardial infarction (STEMI). Despite timely reperfusion by PPCI and restoration of epicardial blood flow in up to 95% of patients, tissue reperfusion remains suboptimal in a sizeable proportion of patients with STEMI. Over the years mechanical and pharmacological strategies to enhance myocardial salvage during PPCI have been developed and used in patients with STEMI. The most common mechanical strategies used in the setting of PPCI include: coronary stenting, direct stenting, mesh-covered stents, self-expanding stents, deferred stenting, thrombectomy, distal protection devices, intra-aortic balloon pumping, left ventricular assist devices and ischaemic conditioning. These strategies are thought to enhance myocardial salvage via improving acute procedural success, attenuation of distal embolisation, microvascular obstruction and reperfusion injury, and providing haemodynamic support. Coronary (direct) stenting is almost the default approach of reperfusion during PPCI procedures. Evidence on the use of mesh-covered stents, self-expanding stents, deferred stenting or left ventricular assist devices is scant and their use in the setting of PPCI remains limited. Mechanical thrombectomy, distal protection devices or routine intra-aortic balloon counterpulsation seem to offer no clinical benefit when used in the setting of PPCI. Although manual aspiration may improve indices of tissue reperfusion, recent research showed no clinical benefit of routine use of this strategy in patients with STEMI undergoing PPCI. Ischaemic conditioning, although promising, remains at an investigational stage and needs further research.

The MGuard coronary stent: safety, efficacy, and clinical utility

Atheromatous and thrombotic embolization during percutaneous coronary revascularization is a feared complication that may cause impaired myocardial reperfusion even with a patent epicardial vessel. The MGuard stent is a cobalt chromium bare metal stent with a porous net attached to its outer surface that has been designed to prevent thrombus fragmentation and distal embolization during stent implantation. This review summarizes the available evidence supporting the use of the MGuard stent in different scenarios such as lesions with high thrombus burden, saphenous vein graft interventions, coronary perforations, or carotid lesions.

Alternative stents in ST-segment elevation myocardial infarction: improving the efficacy of primary percutaneous coronary intervention

Despite the efficacy of primary percutaneous coronary intervention in achieving epicardial reperfusion in ST-segment elevation myocardial infarction, it is often limited by impaired microvascular perfusion attributable to distal embolization of plaque and thrombus, and stent malappostion due to vessel constriction and thrombus apposition, attenuating the full benefits of myocardial reperfusion and resulting in unfavorable clinical outcomes. In the long run implantation of permanent metallic implants have negative effect the biological behavior of the target vessel with a continuous low device failure over the years. Recently, however, efforts have been realized to tackle these shortcomings and optimize mechanical reperfusion by improvements to stent design, as substantiated by the self-expanding stent, the mesh-covered stent and the bioresorbable vascular scaffold. In this article, we provide an overview of the role of these novel, innovatively designed, alternative devices in patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction.

Impact of thrombus burden on outcomes after standard versus mesh-covered stents in acute myocardial infarction (from the MGuard for acute ST elevation reperfusion trial)

Large thrombus burden negatively affects the results of percutaneous coronary intervention (PCI) for acute ST-segment elevation myocardial infarction (STEMI). We investigated the impact of thrombus burden in patients with STEMI undergoing primary PCI with the mesh-covered MGuard stent (InspireMD Ltd., Tel Aviv, Israel) versus a control bare-metal or drug-eluting stent. In 433 patients with STEMI randomized to the MGuard stent versus a control stent, angiographically visible thrombus was identified in 383 patients (88.5%), with median thrombus area 30.15 mm(2) (22.70, 41.93). Lesions with large thrombus (area > median) were treated with more frequent use of manual aspiration (80.8% vs 65.8%, p = 0.0009) and longer (22.1 ± 5.9 vs 19.4 ± 5.4 mm, p <0.0001) and larger (3.46 ± 0.40 vs 3.29 ± 0.36 mm, p <0.0001) stents. PCI of lesions with large thrombus burden had more thrombotic complications (30.6% vs 15.9%, p = 0.0007) and reduced angiographic success (80.3% vs 91.1%, p = 0.003). In large thrombus lesions, the MGuard stent was more effective than control stents in achieving Thrombolysis In Myocardial Infarction-3 flow (87.9% vs 74.5%, p = 0.02) and tended to result in less slow flow or no reflow (8.8% vs 17.6%, p = 0.07). ST-segment resolution was improved with the MGuard, and clinical outcomes were favorable in both stent groups, regardless of thrombus burden. In conclusion, reperfusion success is reduced after primary PCI in lesions with large thrombus burden, an outcome that may be modified by the MGuard stent.

Real world comparison of the MGuard Stent versus the bare metal stent for ST elevation myocardial infarction (the REWARD-MI study)

AIM

The MGuard Stent (MGS) was designed to prevent distal embolization of thrombus and has been shown to improve microcirculation in ST-elevation myocardial infarction (STEMI). However, there are no real world data comparing it with the bare metal stent (BMS). The aim of this study is to determine the efficacy and safety of the MGS in STEMI in the real world compared to the BMS.

METHODS AND RESULTS

In total, 262 patients were included from a single centre, of which 35.9% had an MGS implanted. Two groups of 79 patients were established after propensity score matching, and they were similar in terms of baseline and periprocedural variables. The mean follow-up was 321 ± 12.94 days. There was no difference in mortality (7.6% in both groups), major adverse cardiac events (20.3% vs. 12.7%, P = 0.198), non-cardiac mortality, or non-fatal myocardial infarction (6.3% in both groups). Target lesion revascularization (TLR) was significantly higher in the MGS group (11.4% (9) vs. 1.3% (1) P < 0.01; RR 10.02 [1.23-81.16]).

CONCLUSION

Our study is the first to compare the MGS with the BMS in STEMI in the real world, and it also appears to confirm that although the MGS is a safe device in STEMI that is not associated with increased mortality, it is associated with a higher long-term TLR rate. © 2014 Wiley Periodicals, Inc.