Multicentre experience with MGuard net protective stent in ST-elevation myocardial infarction: safety, feasibility, and impact on myocardial reperfusion

Coronary microvascular obstruction and dysfunction in patients with acute myocardial infarction

Despite prompt epicardial recanalization in patients presenting with ST-segment elevation myocardial infarction (STEMI), coronary microvascular obstruction and dysfunction (CMVO) is still fairly common and is associated with poor prognosis. Various pharmacological and mechanical strategies to treat CMVO have been proposed, but the positive results reported in preclinical and small proof-of-concept studies have not translated into benefits in large clinical trials conducted in the modern treatment setting of patients with STEMI. Therefore, the optimal management of these patients remains a topic of debate. In this Review, we appraise the pathophysiological mechanisms of CMVO, explore the evidence and provide future perspectives on strategies to be implemented to reduce the incidence of CMVO and improve prognosis in patients with STEMI.

No reflow phenomenon in percutaneous coronary interventions in ST-segment elevation myocardial infarction

Percutaneous coronary intervention (PCI) is effective in opening the infarct related artery and restoring thrombolysis in myocardial infarction flow 3 (TIMI-flow 3) in large majority of ST-elevation myocardial infarction (STEMI). However there remain a small but significant proportion of patients, who continue to manifest diminished myocardial reperfusion despite successful opening of the obstructed epicardial artery. This phenomenon is called no-reflow. Clinically it manifests with recurrence of chest pain and dyspnea and may progress to cardiogenic shock, cardiac arrest, serious arrhythmias and acute heart failure. No reflow is regarded as independent predictor of death or recurrent myocardial infarction. No reflow is a multi-factorial phenomenon. However micro embolization of atherothrombotic debris during PCI remains the principal mechanism responsible for microvascular obstruction. This review summarizes the pathogenesis, diagnostic methods and the results of various recent randomized trials and studies on the prevention and management of no-reflow.

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.

Mesh-covered embolic protection stent implantation in ST-segment-elevation myocardial infarction: final 1-year clinical and angiographic results from the MGUARD for acute ST elevation reperfusion trial

BACKGROUND

The MGuard, a bare metal stent covered with a polymer mesh, was designed to reduce distal embolization during percutaneous coronary intervention in ST-segment-elevation myocardial infarction. In the MGUARD for Acute ST Elevation Reperfusion trial, the primary end point of complete ST-segment resolution was significantly improved with the MGuard compared with control. We evaluated 1-year clinical and angiographic results.

METHODS AND RESULTS

Patients with ST-segment-elevation myocardial infarction ≤12 hours undergoing primary percutaneous coronary intervention of a single de novo native lesion were randomized to the MGuard versus any commercially available metallic stent (39.8% drug-eluting). Clinical follow-up was performed through 1 year, and angiography at 13 months was planned in 50 MGuard patients. There was no difference in major adverse cardiac events (1.8% versus 2.3%; P=0.75) at 30 days between the groups. Major adverse cardiac events at 1 year were higher with the MGuard, driven by greater ischemia-driven target lesion revascularization (8.6% versus 0.9%; P=0.0003). Conversely, mortality tended to be lower with the MGuard at 30 days (0% versus 1.9%; P=0.04) and at 1 year (1.0% versus 3.3%; P=0.09). Late lumen loss at 13 months in the MGuard was 0.99±0.80 mm, and binary restenosis was 31.6%.

CONCLUSIONS

In patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention, a trend toward reduced 1-year mortality was present in patients treated with the MGuard stent. Target lesion revascularization and major adverse cardiac events rates during follow-up were higher in the MGuard group than in the control stent group, and angiographic late loss of the MGuard was consistent with that expected from bare metal stents.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01368471.

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.

Coronary thrombus in patients undergoing primary PCI for STEMI: Prognostic significance and management

Acute ST-elevation myocardial infarction (STEMI) usually results from coronary atherosclerotic plaque disruption with superimposed thrombus formation. Detection of coronary thrombi is a poor prognostic indicator, which is mostly proportional to their size and composition. Particularly, intracoronary thrombi impair both epicardial blood flow and myocardial perfusion, by occluding major coronary arteries and causing distal embolization, respectively. Thus, although primary percutaneous coronary intervention is the preferred treatement strategy in STEMI setting, the associated use of adjunctive antithrombotic drugs and/or percutaneous thrombectomy is crucial to optimize therapy of STEMI patients, by improving either angiographical and clinical outcomes. This review article will focus on the prognostic significance of intracoronary thrombi and on current antithrombotic pharmacological and interventional strategies used in the setting of STEMI to manage thrombotic lesions.

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.

No-reflow phenomenon: pathophysiology, diagnosis, prevention, and treatment. A review of the current literature and future perspectives

No-reflow is responsible for 40% of the primary percutaneous coronary intervention without complete myocardial reperfusion despite successful reopening of the infarct-related artery. This review describes the main pathophysiological mechanisms of no-reflow, its clinical manifestation, including the strong association with increased in-hospital mortality, malignant arrhythmias, and cardiac failure as well as the diagnostic methods. The latter ranges from simple angiographic thrombolysis in myocardial infarction grade score to more complex angiographic indexes, imaging techniques such as myocardial contrast echo or cardiac magnetic resonance, and surrogate clinical end points such as ST-segment resolution. This review also summarizes the strategies of prevention and treatment of no-reflow, considering the most recent studies results regarding medical therapy and devices.

Risk of acute myocardial infarction after transurethral resection of prostate in elderly

Background

Benign prostatic hyperplasia is a frequent disease among elderly, and is responsible for considerable disability. Benign prostatic hyperplasia can be clinically significant due to lower urinary tract symptoms that take place because the gland is enlarged and obstructs urine flow. Transurethral resection of the prostate remains the gold standard treatment for patients with moderate or severe symptoms who need active treatment or who either fail or do not want medical therapy. Moreover, perioperative and postoperative surgery complications as cardiovascular ones still occur. The incidence of acute myocardial infarction in patients undergoing transurethral resection of the prostate is controversial. The first studies showed an increase in mortality and relative risk of death from myocardial infarction in transurethral resection of the prostate group vs open prostatectomy but these results are in contrast with more recent data.

Discussion

Given the conflicting evidence of the studies in the literature, in this review we are going to discuss the factors that may influence the risk of myocardial infarction in elderly patients undergoing prostate surgery. We analyzed the possible common factors that lead to the development of myocardial infarction and benign prostatic hyperplasia (cardiovascular and metabolic), the stressor factors related to prostatectomy (surgical and haemodynamic) and the risk factors specific of the elderly population (comorbidity and therapies).

Summary

Although transurethral resection of the prostate is considered at low risk for severe complications, there are several reports indicating that cardiovascular events in elderly patients undergoing this surgical operation are more common than in the general population. Several cardio-metabolic, surgical and aging-related factors may help explain this observation but results in literature are not concord, especially due to the fact that most data derive from retrospective studies in which selection bias cannot be excluded. Subsequently, further studies are necessary to clarify the incidence of acute myocardial infarction in old people.

Microvascular coronary flow comparison in acute myocardial infarction angioplasty treated with a mesh covered stent (MGUARD stent) versus bare metal stent: MICAMI-MGUARD

BACKGROUND

Distal embolization of thrombus/platelet aggregates decreases myocardial reperfusion during primary percutaneous coronary intervention (PCI), and is associated with worse immediate and long-term prognosis of patients with ST-elevation myocardial infarction (STEMI).

OBJECTIVE

Assess the efficacy of a mesh covered stent (MGuard™ stent, MGS) in preventing distal embolization and microvascular reperfusion impairment during primary PCI, compared with a bare metal stent (BMS).

METHODS

Forty patients with STEMI referred for primary PCI were randomized for stenting the culprit lesion with the MGS (n = 20) or a BMS (n = 20). Blinded experts performed off-line measurements of angiographic epicardial and microvascular reperfusion criteria: TIMI flow grade, myocardial blush, corrected TIMI frame count (cTFC).

RESULTS

At baseline clinical, angiographic and procedural variables were not different between groups. Post PCI TIMI flow grade was similar in both groups. We observed better myocardial Blush grade in group MGS compared to BMS (median value 3.0 vs 2.5, 2p = 0.006) and cTFC (mean cTFC: MGS 19.65 ± 4.07 vs BMS 27.35 ± 7.15, 2p < 0.001, cTFC mean difference MGS-BMS: 7.7, CI 95%: 3.94 to 11.46). MGS stent group had a higher percentage of successful angioplasty (cTFC ≤ 23: MGS 85% vs BMS 30%, 2p < 0.001). We had two cases of acute stent thrombosis (one for each group) at 30days follow up, but no clinical events at 6 months follow up.

CONCLUSIONS

In this exploratory study, MGS significantly improved microvascular reperfusion criteria compared with a BMS in primary PCI. However its safety and impact on clinical outcomes should be verified in larger randomized clinical trials.

Closed versus open cell stent for high-risk percutaneous coronary interventions in ST-elevation acute myocardial infarction: the Closed versus Open Cells stent for High risk percutaneous coronary Interventions in ST-Elevation acute myocardial infarction (COCHISE) pilot study

BACKGROUND

Stent deployment may be associated with distal embolization and slow flow in coronary thrombotic lesions. There are no data on the risk of distal thrombus embolization according to the stent design. The aim was to evaluate coronary flow after percutaneous coronary interventions (PCI) in acute myocardial infarction according to the employed stent (closed versus open cell design).

METHODS

From March 2010 to December 2011, 223 consecutive patients with acute ST-elevation myocardial infarction were randomized to primary PCI either with an open cell (112 patients, 88 men) or with a closed cell stent design (111 patients, 92 men). The primary endpoint was the corrected TIMI frame count (cTFC) after the procedure.

RESULTS

There were no significant differences in procedural success nor in-stent deployment in the 2 groups. At baseline, there were no significant differences in cTFC between the 2 groups (70 ± 37 and 67 ± 39, P = .65, respectively). After the procedure, the open cell group showed significantly higher cTFC compared to the closed cell group (18 ± 11 and 15 ± 5, P = .003 respectively). This difference was associated with a significant lower rate of TIMI 3 flow (87% and 95%, P = .037) and myocardial blush grade 3 (65% and 87%, P = .001) in the open compared to the closed cell group. There were 2 cases of death in the open cell and 1 case in the closed cell group.

CONCLUSIONS

The use of a closed cell stent design rather than an open cell during PCI for acute ST-elevation myocardial infarction is associated with better coronary angiographic flow after PCI.

MGUard versus bAre-metal stents plus manual thRombectomy in ST-elevation myocarDial infarction pAtieNts-(GUARDIAN) trial: study design and rationale

BACKGROUND

Distal embolization may decrease coronary and myocardial reperfusion after percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI). In this setting, manual thrombectomy (MT) resulted in better perfusion and clinical outcomes when compared with "conventional" PCI (direct stenting or stenting after predilation). MGuard net protective stent (MGS, Inspire-MD, Tel-Aviv, Israel) is a new bare-metal stent (BMS) with a polyethylene theraphthalate mesh coverage anchored to the external surface of the struts aiming to minimize distal embolization during PCI.

PURPOSE

We intend to determine whether MGS implantation is comparable with a strategy of MT pretreatment followed by BMS deployment.

STUDY DESIGN

The MGUard versus bAre-metal stents plus manual thRombectomy in ST-elevation myocarDial Infarction pAtieNts (GUARDIAN) is a multicentre, prospective, randomized, noninferiority, open-label trial with a planned inclusion of 556 STEMI patients. Patients are assigned to treatment with MGS or MT pretreatment followed by BMS implantation in the infarct-related artery. All patients are treated medically according to current international guidelines. Randomization is performed before coronary angiography. The primary endpoint is complete (≥ 70%) ST-segment resolution at 60 min after PCI. Secondary endpoints are thrombolysis in myocardial infarction (TIMI) coronary flow grade ≥ 2, corrected TIMI frame count <23, myocardial blush grade of the infarct related area ≥ 2, and major adverse cardiac events rate at 30-day, 6-month, and 1-year follow-up. A cardiac magnetic resonance imaging substudy is planned to investigate microvascular obstruction and infarct size area reduction, at prespecified time-points, among 80 consecutive patients enrolled.

CONCLUSIONS

If MGS implantation is noninferior to a strategy of MT pretreatment followed by BMS deployment, it will lend support to the use of this treatment as another possible option for STEMI patients undergoing PCI.

[Evidence-based management of ST-segment elevation myocardial infarction (STEMI). Latest guidelines of the European Society of Cardiology (ESC) 2010]

Acute myocardial infarction and its consequences (death, chronic ischemic coronary artery disease, heart failure) are still the number 1 causes of death and of cardiovascular diseases in Germany. In this context, patients with STEMI are at the highest risk. The first-line management of STEMI patients often determines if the outcome is life or death. This overview presents the current optimal evidence-based management of STEMI patients as a practice-oriented extract according to the latest ESC guidelines, fully published some weeks ago (http://www.escardio.org).All efforts must be made to keep the respective time intervals between the onset of symptoms and the beginning of reperfusion therapy as short as possible, i.e. best within a dedicated STEMI network. Two of the time intervals are particularly essential: the time delay between the onset of symptoms and the first medical contact (FMC) and the time delay between FMC and the beginning of reperfusion. The time delay between the onset of symptoms and FMC depends on the patient as well as on the organization of the emergency medical service (EMS). Unfortunately, too many patients/bystanders still hesitate to immediately call the EMS. More intense measures must therefore be taken to educate the public. The optimal FMC by medical doctors or paramedics reacts quickly and ideally arrives with ECG equipment for immediate diagnosis of STEMI (persistent ST-segment elevation or presumably new left bundle branch block) before hospital admission. Unfortunately in many cases, the FMC is the emergency room of a hospital. Further decisions can be made without laboratory findings. In Germany, the average time delay between onset of symptoms and FMC is 100 min and therefore longer than in some other European countries.The next critical time interval is that between FMC and the beginning of reperfusion: this interval depends solely on the EMS organization and the distance to the next catheter laboratory with 24 h PCI (percutaneous coronary intervention) availability. The key question for further decisions is whether a primary PCI can be performed within 120 min after FMC. If so, the primary PCI should definitively be preferred. In patients <75 years presenting with a large anterior infarction within 2 h after onset of symptoms, this time interval should not exceed 90 min. For primary PCI an often used measure of quality is the "door-to-balloon" time, which should of course be as short as possible. Therefore, patients with STEMI should be admitted directly to the catheterization laboratory bypassing the emergency room or intensive care unit. In Germany, the average time interval between FMC and start of primary PCI is approximately 120 min just at the upper limit of the guideline recommendations. Some other European countries report a significantly shorter corresponding time delay.If primary PCI is not possible within 120 min (or 90 min) after FMC, thrombolysis must be initiated within 30 min after FMC, either in the EMS ambulance or in a nearby non-PCI hospital. A thrombolytic therapy, however, even if "successful", is not the final therapy: within 24 h (but not before 3 h) cardiac catheterization has to be performed with PCI, if applicable. Analyzing the overall revascularization rates in Germany, 81% receive primary PCI, 7% thrombolysis and 12% no reperfusion therapy. Regarding any reperfusion in STEMI, Germany holds the third place after the Czech Republic and Belgium.Patients presenting at 12-24 h after onset of symptoms or later may possibly benefit from a PCI, even if already asymptomatic, if signs of ischemia/viability in the infarct artery-related area are demonstrable. If this cannot be shown, PCI in these patients is not indicated.The first-line medication aims at dual antiplatelet therapy (DAPT) and anticoagulation. For DAPT, the combination of ASA with a thienopyridine is mandatory. If primary PCI is feasible, DAPT with prasugrel (loading dose of 60 mg, independent of age and weight) is preferred due to its faster onset of action and superior effectiveness over clopidogrel (loading dose of 600 mg). In patients with STEMI, prasugrel when compared to clopidogrel significantly reduced nonfatal myocardial infarction after 15 months from 9.0% to 6.8% and stent thrombosis significantly from 2.8% to 1.6% (ARC definite/probable). If, however, there are contraindications against prasugrel (s/p stroke or TIA) or if thrombolysis had to be performed, clopidogrel is the choice for DAPT.The i.v. administration of glycoprotein IIb/IIIa inhibitors (GPI) has been limited to only those patients with a high intracoronary thrombus burden. The upstream application of GPI is not recommended. Recommendations for the mechanical treatment of thrombus burden include manual thrombus aspiration (which was upgraded) and a mesh-based protection stent device (MGuard™). For anticoagulation, unfractionated heparin (UFH) is recommended as always but bivalirudin is an upcoming alternative, either in the catheterization laboratory on top after an EMS-delivered UFH bolus or as a possible first-line monotherapy. Bivalirudin may be preferred in STEMI patients with a high risk of bleeding. To prevent possible thrombotic events after PCI, bivalirudin should be continued for several hours after primary PCI.Regardless of whether PCI or thrombolysis was the first-line therapy and regardless of whether a stent (BMS or DES) was implanted, DAPT should be continued for 12 months with prasugrel 10 mg/day (or 5 mg/day, if ≥75 years old and/or <60 kg body weight) or clopidogrel (75 mg/day). There is no evidence that higher maintenance doses of clopidogrel may circumvent possible clopidogrel resistance. The usefulness of so far non-standardized in-vitro platelet aggregation measurements or the practice-oriented interpretation of genetic tests for CYP2C19 polymorphism is unknown. With the 12 months DAPT the patient is treated not the stent.