M-Guard Stent in Stemi Patients with High Thrombus Burden Lesions: A Prospective, Single Arm Study

Document Type : Original Article

Authors

1 Patient Safety Research Center, Imam Reza Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.

2 Department Cardiology, Imam Reza Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.

3 Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.

Abstract

Introduction: Primary PCI is the preferred modality to restore blood perfusion in STEMI patients, but myocardial reperfusion is sometimes lower than optimal. Distal embolization seems to play the leading role. There is rare evidence suggestive of M-Guard stents; a recent innovation which protects against distal embolization may be beneficial in this circumstance.
Materials and Methods:This was a prospective single arm study. Patients with acute STEMI admitted at the Cardiac Emergency Unit of Imam Reza Hospital from July 2011 to November  2012 who had a large bulk of thrombus in their angiogram, underwent M-Guard stenting and were followed up for six months for chest pain and secondary revascularization.
Results: The 23 patients, aged between 34 and 84; 65.2%, were male and had undergone primary PCI, mechanical thrombus aspiration, and M-Guard stenting. Left Anterior Descending (LAD) (63.9%) and Right Coronary Artery (RCA) (39.1%) were most commonly involved. 78.2%, 13.1%, and 8.9% of patients had primary Thrombolysis in Myocardial Infarction (TIMI) Thrombus grade five, four, and three. Among them, 86.9% achieved TIMI Flow grade three and 13.04% TIMI Flow grade two. The rate of transient "no-reflow" phenomenon was 21%. One patient died after stenting in the setting of cardiogenic shock. There was one case of in-stent restenosis five months after the procedure. Of the other 15 accessible patients, after six months, none experienced a second angioplasty or any ischemic symptoms.
Conclusion: Using M-Guard stents in acute STEMI patients having undergone primary PCI with high thrombus burden is probably associated with lower rates of the "no-reflow" phenomenon and improved vessel reperfusion.
 

Keywords


Introduction

Primary percutaneous coronary intervention (PCI) is the preferred modality to restore blood perfusion in ST-segment Elevation Myocardial Infarction (STEMI) patients (1-3). Various stents and different medications have improved the effect of PCI and developed approximately normal perfusion in the majority of patients (4-6). However, despite the effectiveness of stent implantation during primary PCI for epicardial refl ow, myocardial perfusion is sometimes lower than optimal according to low Myocardial Blush Grade (MBG) and poor resolution of ST-segment elevation in patients undergoing primary PCI. Impaired myocardial reperfusion leads to an increased infracted area size, left sided heart failure, and finally, increased mortality in both short term and long term follow up (7-13).

There are various mechanisms underlying this phenomenon but distal embolization of thrombi and/or fragile atheromatous debri due to PCI, the "no-reflow phenomenon", seems to have the leading role (13-16).

Researchers use different thrombectomy and Protective Emboli Devices (PEDs) and various pharmacological agents to improve post procedural myocardial reperfusion in STEMI patients with conflicting reported results (17-23). M-guard stent is a mesh covered stent which prevents plaque fragmentation and distal embolization during stent implantation (24-26). Several trials have shown that among STEMI patients having undergone primary PCI, compared to Bare Metal Stents (BMS), M-guard stents result in higher rates of epicardial perfusion and complete ST resolution (24, 27, 28).

However, there is rare evidence suggestive for M-guard stenting in culprit vessels with a large thrombus bulk with or without primary mechanical aspiration (24). In the present study patients with acute STEMI who had a large bulk of thrombus in their angiogram, underwent M-Guard stenting and acute and long term outcomes were evaluated.

Materials and Methods

Study design: All patients with acute STEMI admitted to the Cardiac Emergency Unit of Imam Reza Hospital, Mashhad, Iran from July 2011 to November 2012 who underwent angiography and had a large thrombus bulk in their angiogram were considered as eligible for further evaluations. This was a prospective, single case group study in which the inclusion criteria was as follows:

1. Acute STEMI (persistent chest pain more than 30 minutes and less than 12 hours and ≥ 2mm ST-segment elevation in V1 –V3 leads or ≥1mm in at least 2 other contiguous electrocardiographic leads).

2. Evidence of a large thrombus bulk on coronary angiogram (TIMI thrombus grade 4-5)

3. No severe tortuosity or heavy calcification in the culprit vessel.

4. Vessel size estimated visually ≥ 3 mm and ≤ 4 mm in diameter.

The study protocol was approved by the Medical Ethics Committee of Mashhad University of Medical Sciences and a written informed consent was obtained from each patient prior to study entrance.

Study device: The M-guard stent is a recent innovation for the prevention of distal embolization of thrombi or plaque debri during stent implantation. It is made of a bared metal stent, covered with a tiny (in micron level) mesh.The bare metal stent is an expandable balloon made of stainless steel, and the mesh is of polyethylene terephthalate microfiber. Stents of three to four mm in diameter and 19 to 39 mm in length were used during this study.

Procedure:Immediately after confirming the diagnosis of Acute STEMI by ECG, the patients were administered 300 mg Aspirin, 600 mg Clopidogrel as well as Beta Blockers, Statins and Nitrates. With a time of Door to Balloon less than 90 minutes, selected patients for primary PCI underwent angiography, and those with a high burden of thrombus (TIMI grade four-five) were selected for primary angioplasty using M-guarded stents. 60 to 90 minutes after the procedure, a control ECG was taken. IIb-IIIa inhibitors (Eptifibatide) were used in only three patients. All patients were prescribed at least five types of medications on their discharge order including: Aspirin, Clopidogrel, Statins, Angiotensin Converting Enzyme (ACE) inhibitors and Beta blockers. All patients were visited monthly by a single cardiologist, and at six months of clinical follow- up, they were contacted by telephone to ask for cardiac symptoms and find out whether they required re-angioplasty on their stent.

Results

This study investigated 23 patients with acute STEMI admitted to the Cardiac Emergency Unit of Imam Reza Hospital, Mashhad from July 2011 to November 2012 who underwent Percutaneous Coronary Intervention (PCI) with Mesh Guard stent.

Demographic data of the patients is shown in Table1.

63.9% of the patients had lesions in their LAD artery, and in 39.1%, the RCA was involved. In every patient, only one lesion was treated. After angiography and primary thrombus aspiration (in 20 patients), 87% of patients still had no flow in their culprit vessel (TIMI thrombus grade five and TIMI flow grade zero-one).

Stent implantation was done successfully in all patients, and there was no dislodgement or peripheral stent embolization during stenting. Stents with a length of 19 to 39 mm (mean: 28.78 mm) and a diameter of three to four mm (mean: 3.22 mm) were deployed.

High-pressure stent inflation (at least 14 atm) was performed in every patient (Table-1). In three patients, post dilatation with noncompliant balloon was done due to obvious non-expanded stents. TIMI flow grade three was attained in 87% of patients after stenting. Among the 78.28% of patients with primary TIMI thrombus grade 5, 65. 22% achieved TIMI flow grade three, and 13.04% reached TIMI flow grade two after M-guard stent deployment. All patients with a smaller thrombus bulk experienced complete reperfusion after stent implantation. The rate of transient "no-reflow" phenomenon was 21.7%. One patient died after successful stenting due to cardiogenic shock at the time of admission.  There was one case of diffuse in-stent restenosis five months after primary PCI in ostioproximal LAD in a 49-year-old diabetic male.

After six months, only 15 out of 22 patients were accessible by telephone. They all mentioned monthly visits by a non-faculty cardiologist. None of them experienced secondary angioplasty during the six months of follow-up.

Discussion

To date, different studies have supported the PCI strategy in acute STEMI patients as a therapeutic option (1-5) and reported significant results in restoring blood flow in involved vessels (4-6). However, this epicardial blood flow is not always associated with effective flow in myocardial microcirculation level as reflected in low rates of MBG (Myocardial Blush Grade) and poor ST resolution (7-11,29,30). Moreover, large thrombus bulk in acute STEMI patients undergoing primary PCI results in an increased risk of distal embolization and causes poor myocardial perfusion (13,16). A prospective, randomized, multicenter study on Polyethylene Terephthalate Micronet Mesh-Covered stents in STEMI patients (The MASTER Trial) showed that using M-guard stents results in lower rates of distal embolization and in addition to effective epicardial blood flow, improves myocardial perfusion (27) besides decreasing the rate of mortality and adverse cardiac events (26). Different studies with controversial results have been performed focusing on other protection devices for distal embolization; they include Proximal and Distal Protection Devices and Thrombectomy Catheters (31-33). Distal Balloons create high MBG and TIMI Flow grade while Distal Filters do not. No significant effect on ST-resolution, prevention of no-reflow phenomenon or decreasing the risk of distal embolization has been reported for either of them (33). Also, two Meta analyses on the mechanical protection devices have shown that despite the improved myocardial perfusion and decreased distal embolization, the survival rate demonstrates no significant change (31, 32). Numerous studies have suggested that mechanical aspiration along with PCI reduces mortality (17, 34, 35); yet aspiration has the risk of distal embolization (36).

In the current study patients with a large thrombus bulk in spite of primary thrombosuction, which reflected their high risk for distal embolization, were treated by Mguard stents. Our endpoint measures included TIMI Flow grade as a marker of epicardial blood flow, the rate of no-reflow phenomenon, six months clinical follow up of chest pain, the need for revascularization therapy, and mortality. Achieving a high rate of TIMI flow grade three (87%), low rates of no-reflow phenomenon (21%), and no mortality in six month follow-up are all in favor of the hypothesis that deploying M-Guard stents results in restoring effective blood flow in culprit vessels, reduces the risk of distal embolization, and creates near optimal myocardial perfusion which are reflected in the lower rates of target lesion revascularization and mortality, thus resulting in a higher survival rate. Although a secondary angiography is required to comment on restenosis formation more precisely, our clinical outcomes did not suggest it. The small number of cases, missing out on some patients during follow-up, and being a single arm study with no control group were the main limitations of our study.

Conclusion

This prospective single arm study suggests that using Mesh guard stents in acute ST-segment Elevation Myocardial Infarction (STEMI) patients who undergo primary percutaneous intervention (P-PCI) and despite thrombus aspiration still have a high burden of thrombus, may probably be associated with lower rates of the no-reflow phenomenon and improved flow of the culprit vessel. Extended controlled trials will be a matter of benefit.

1- Van de Werf F, Bax J, Betriu A, Blomstrom-Lundqvist C, Crea F, Falk V, et al. Management of acute myocardial infarction in patients presenting with persistent ST-segment elevation: the Task Force on the Management of ST-Segment Elevation Acute Myocardial Infarction of the European Society of Cardiology. European heart journal. 2008 Dec;29(23):2909-45.
2- Keeley EC, Boura JA, Grines CL. Primary angioplasty versus intravenous thrombolytic therapy for acute myocardial infarction: a quantitative review of 23 randomised trials. Lancet. 2003 Jan 4;361(9351):13-20.
3- Nabel EG, Braunwald E. A tale of coronary artery disease and myocardial infarction. The New England journal of medicine. 2012 Jan 5;366(1):54-63.
4- Steg PG, James SK, Atar D, Badano LP, Blomstrom-Lundqvist C, Borger MA, et al. ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. European heart journal. 2012 Oct;33(20):2569-619.
5- Silber S, Albertsson P, Aviles FF, Camici PG, Colombo A, Hamm C, et al. Guidelines for percutaneous coronary interventions.The Task Force for Percutaneous Coronary Interventions of the
European Society of Cardiology. European heart journal. 2005 Apr;26(8):804-47.
6- Mehta RH, Harjai KJ, Cox D, Stone GW, Brodie B, Boura J, et al. Clinical and angiographic correlates and outcomes of suboptimal coronary flow inpatients with acute myocardial infarction undergoing primary percutaneous coronary intervention. Journal of the American College of Cardiology. 2003 Nov 19;42(10):1739-46.
7- Claeys MJ, Bosmans J, Veenstra L, Jorens P, De Raedt H, Vrints CJ. Determinants and prognostic implications of persistent ST-segment elevation after primary angioplasty for acute myocardial infarction: importance of microvascular reperfusion injury on clinical outcome. Circulation. 1999 Apr 20;99(15):1972-7.
8- Kondo M, Nakano A, Saito D, Shimono Y. Assessment of "microvascular no-reflow phenomenon" using technetium-99m macroaggregated albumin scintigraphy in patients with acute myocardial infarction. Journal of the American College of Cardiology. 1998 Oct;32(4):898-903.
9- Maes A, Van de Werf F, Nuyts J, Bormans G, Desmet W, Mortelmans L. Impaired myocardial tissue perfusion early after successful thrombolysis. Impact on myocardial flow, metabolism, and function at late follow-up. Circulation. 1995 Oct 15;92(8):2072-8.
10- Stone GW, Peterson MA, Lansky AJ, Dangas G, Mehran R, Leon MB. Impact of normalized myocardial perfusion after successful angioplasty in acute myocardial infarction. Journal of the American College of Cardiology. 2002 Feb 20;39(4):591-7.
11- Van 't Hof AW, Liem A, Suryapranata H, Hoorntje JC, de Boer MJ, Zijlstra F. Angiographic assessment of myocardial reperfusion in patients treated with primary angioplasty for acute myocardial infarction: myocardial blush grade. Zwolle Myocardial Infarction Study Group. Circulation. 1998 Jun 16;97(23):2302-6.
12- Mamas MA, Fraser D, Fath-Ordoubadi F. The role of thrombectomy and distal protection devices during percutaneous coronary interventions. EuroIntervention: journal of EuroPCR in collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology. 2008 May;4(1):115-23.
13- Henriques JP, Zijlstra F, Ottervanger JP, de Boer MJ, van 't Hof AW, Hoorntje JC, et al. Incidence and clinical significance of distal embolization during primary angioplasty for acute myocardial infarction. European heart journal. 2002 Jul;23(14):1112-7.
14- Erbel R, Heusch G. Coronary microembolization--its role in acute coronary syndromes and interventions. Herz. 1999 Nov;24(7):558-75.
15- Schwartz RS, Burke A, Farb A, Kaye D, Lesser JR, Henry TD, et al. Microemboli and microvascular obstruction in acute coronary thrombosis and sudden coronary death: relation to epicardial plaque histopathology. Journal of the American College of Cardiology. 2009 Dec 1;54(23):2167-73.
16- Napodano M, Ramondo A, Tarantini G, Peluso D, Compagno S, Fraccaro C, et al. Predictors and time-related impact of distal embolization during primary angioplasty. European heart journal. 2009 Feb;30(3):305-13.
17- Svilaas T, Vlaar PJ, van der Horst IC, Diercks GF, de Smet BJ, van den Heuvel AF, et al. Thrombus aspiration during primary percutaneous coronary intervention. The New England journal of medicine. 2008 Feb 7;358(6):557-67.
18- Inaba Y, Chen JA, Mehta N, Bergmann SR. Impact of single or multicentre study design on the results of trials examining the efficacy of adjunctive devices to prevent distal embolisation during acute myocardial infarction. EuroIntervention: journal of EuroPCR in collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology. 2009 Aug;5(3):375-83.
19- Thiele H, Wohrle J, Hambrecht R, Rittger H, Birkemeyer R, Lauer B, et al. Intracoronary versus intravenous bolus abciximab during primary percutaneous coronary intervention in patients with acute ST-elevation myocardial infarction: a randomised trial. Lancet. 2012 Mar 10;379(9819):923-31.
20- Stone GW, Maehara A, Witzenbichler B, Godlewski J, Parise H, Dambrink JH, et al. Intracoronary abciximab and aspiration thrombectomy in patients with large anterior myocardial infarction: the INFUSE-AMI randomized trial. JAMA: the journal of the American Medical Association. 2012 May 2;307(17):1817-26.
21- Migliorini A, Stabile A, Rodriguez AE, Gandolfo C, Rodriguez Granillo AM, Valenti R, et al. Comparison of AngioJet rheolytic thrombectomy before direct infarct artery stenting with direct stenting alone in patients with acute myocardial infarction. The JETSTENT trial. Journal of the American College of Cardiology. 2010 Oct 12;56(16):1298-306.
22- Liistro F, Grotti S, Angioli P, Falsini G, Ducci K, Baldassarre S, et al. Impact of thrombus aspiration on myocardial tissue reperfusion and left ventricular functional recovery and remodeling after primary angioplasty. Circulation Cardiovascular interventions. 2009 Oct;2(5):376-83.
23- Chevalier B, Gilard M, Lang I, Commeau P, Roosen J, Hanssen M, et al. Systematic primary aspiration in acute myocardial percutaneous intervention: a multicentre randomised controlled trial of the export aspiration catheter. EuroIntervention: journal of EuroPCR in collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology. 2008 Aug;4(2):222-8.
24- Romaguera R, Gomez-Hospital JA, Sanchez-Elvira G, Gomez-Lara J, Ferreiro JL, Roura G, et al. MGuard mesh-covered stent for treatment of ST-segment elevation myocardial infarction with high thrombus burden despite manual aspiration. Journal of interventional cardiology. 2013 Feb;26(1):1-7.
25- Silva-Orrego P, Colombo P, Bigi R, Gregori D, Delgado A, Salvade P, et al. Thrombus aspiration before primary angioplasty improves myocardial reperfusion in acute myocardial infarction: the DEAR-MI (Dethrombosis to Enhance Acute Reperfusion in Myocardial Infarction) study. Journal of the American College of Cardiology. 2006 Oct 17;48(8):1552-9.
26- Dudek D, Dziewierz A, Rzeszutko L, Legutko J, Dobrowolski W, Rakowski T, et al. Mesh covered stent in ST-segment elevation myocardial infarction. EuroIntervention: journal of EuroPCR in collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology. 2010 Nov;6(5):582-9.
27- Stone GW, Abizaid A, Silber S, Dizon JM, Merkely B, Costa RA, et al. Prospective, Randomized, Multicenter Evaluation of a Polyethylene Terephthalate Micronet Mesh-Covered Stent (MGuard) in ST-Segment Elevation Myocardial Infarction: The MASTER Trial. Journal of the American College of Cardiology. 2012 Sep 28: 1975-84.
28- Kaluski E, Groothuis A, Klapholz M, Seifart P, Edelman E. Coronary stenting with M-Guard: feasibility and safety porcine trial. The Journal of invasive cardiology. 2007 Aug;19(8):326-30.
29- Claeys MJ, Bosmans J, Veenstra L, Jorens P, De Raedt H, Vrints CJ. Determinants and prognostic implications of persistent ST-segment elevation after primary angioplasty for acute myocardial infarction: importance of microvascular reperfusion injury on clinical outcome. Circulation. 1999 Apr 20;99(15):1972-7.
30- De Luca G, van 't Hof AW, Ottervanger JP, Hoorntje JC, Gosselink AT, Dambrink JH, et al. Unsuccessful reperfusion in patients with ST-segment elevation myocardial infarction treated by primary angioplasty. American heart journal. 2005 Sep;150(3):557-62.
31- De Luca G, Suryapranata H, Stone GW, Antoniucci D, Neumann FJ, Chiariello M. Adjunctive mechanical devices to prevent distal embolization in patients undergoing mechanical revascularization for acute myocardial infarction: a meta-analysis of randomized trials. American heart journal. 2007 Mar;153(3):343-53.
32- Burzotta F, Testa L, Giannico F, Biondi-Zoccai GG, Trani C, Romagnoli E, et al. Adjunctive devices in primary or rescue PCI: a meta-analysis of randomized trials. International journal of cardiology. 2008 Jan 24;123(3):313-21.
33- Sobieraj DM, White CM, Kluger J, Tongbram V, Colby J, Chen WT, et al. Systematic review: comparative effectiveness of adjunctive devices in patients with ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention of native vessels. BMC cardiovascular disorders. 2011 Dec;11:74.
34- De Luca G, Dudek D, Sardella G, Marino P, Chevalier B, Zijlstra F. Adjunctive manual thrombectomy improves myocardial perfusion and mortality in patients undergoing primary percutaneous coronary intervention for ST-elevation myocardial infarction: a meta-analysis of randomized trials. European heart journal. 2008 Dec;29(24):3002-10.
35- Dudek D, Mielecki W, Burzotta F, Gasior M, Witkowski A, Horvath IG, et al. Thrombus aspiration followed by direct stenting: a novel strategy of primary percutaneous coronary intervention in ST-segment elevation myocardial infarction. Results of the Polish-Italian-Hungarian RAndomized ThrombEctomy Trial (PIHRATE Trial). American heart journal. 2010 Nov;160(5):966-72.
36- Fokkema ML, Vlaar PJ, Svilaas T, Vogelzang M, Amo D, Diercks GF, et al. Incidence and clinical consequences of distal embolization on the coronary angiogram after percutaneous coronary intervention for ST-elevation myocardial infarction. European heart journal. 2009 Apr;30(8):908-15.