Catheterization and Cardiovascular Interventions 71:84-91 (2008)
The Effect of Thrombectomy on Myocardial Blush
in Primary Angioplasty: The Randomized Evaluation
of Thrombus Aspiration by Two Thrombectomy Devices
in Acute Myocardiai Infarction (RETAMI) Trial
Background: In patients with ST-segment elevation myocardial infarction (STEMI), primary percutaneous coronary intervention (PCI) may cause thrombus dislodgment lead-ing to microvascular function impairment, which is a negative independent predictor of myocardial function recovery. Compared with conventional stenting, pretreatment with aspiration thrombectomy during primary PCI significantly improves coronary epicardial flow and myocardial tissue perfusion parameters. We sought to evaluate the angio-graphic findings of two different manual aspiration thrombectomy devices (Diver-lnva-tec (DI) and Export-Medtronic (EM)) in STEMI patients undergoing primary angio-plasty. Methods: We randomized 103 STEMI patients referred to our hospital to undergo primary PCI (<12 n =" 52)" n =" 51)">2, and post-stenting myocardial blush grade (MBG) >2 in the two groups. Resulte: Baseline, clinical, and angiographic preprocedural findings did not differ between the two groups. After aspiration thrombectomy, a TS < p =" 0.0052)."> 2 (69.3 vs. 92.2%, P = 0.0052) and post-stenting MBG >2 (88.2 vs. 69.3%, P = 0.029) were significantly higher in EM group. No significative differences were observed in terms of clinical events at 1 and 12 months. Conclusions: In this single-center, prospective, randomized study, a EM use before stenting iñ STEMI patients seems to remove more thrombotic burden compared with DI, providing a greater post-thrombectomy epicardial flow and a better post-stenting microvascular perfusión. > zoos w¡iey-uss, inc.
Key words: primary angioplasty; ST-elevation myocardial infarction; thrombus; manual aspiration thrombectomy
INTRODUCTION
ST-segment elevation myocardial infarction (STEMI) is typically caused by occlusive coronary thrombus formation on an activated atherosclerotic plaque. Percutaneous coronary intervention (PCI) using coronary stent implantation and glycoprotein IlbIIIa inhibitors administration are considered as standard treatments in this setting [1-3], increasing the rate of thrombolysis in myocardial infarction (TIMI) flow grade on the infarctrelated artery [4,5]. However, myocardial tissue reperfusion is often reduced due to the occurrence of distal atherothombotic debris embolization, and this may limit the efficacy of primary PCI [6]. Recent studies suggest that manual aspiration thrombectomy during primary PCI, in patients with intracoronary, angiographically visible thrombus, can prevent distal embolization, improving myocardial perfusión and reducing the incidence of left ventricular remodeling [7-10].
Despite several systems for intracoronary thrombectomy that differ considerably in construction, principies of operation and management have been introduced into the clinical practice with a widespread use in the setting of primary PCI [11], comparative data are still lacking. The aim of the present randomized study was to evaluate the effects of two different manual aspiration thrombectomy devices (Diver-Invatec (DI) and Export-Medtronic (EM)) on angiographic parameters of epicardial flow and myocardial tissue reperfusion in STEMI patients undergoing primary angioplasty.
METHODS
Study Population
Consecutive patients admitted to our department with STEMI between January 2005 and February 2006 to undergo primary PCI have been enrolled in this study. The inclusion criteria were: diagnosis of STEMI (evidence of ischemic chest pain for >30 min and new ST-segment elevation >2 mm in at least two contiguous electrocardiographic leads) within 12 hr from symptoms onset, de novo coronary artery lesion, occluded single native vessel >2.5 mm in diameter, angiographically identifiable thrombus (presence of a filling defect within the coronary lumen surrounded by contrast medium observed in multiple projections, without calcium within the filling defect or persistence of contrast medium within the coronary lumen) [12,13], TIMI flow grade 0-1, and age >18 years.
Main exclusion criteria were: previous PCI on IRA, rescue PCI, previous myocardial infarction (MI) or coronary artery bypass grafting, and current participation in another study.
Study Protocol and Procedure
All patients were pretreated with aspirin 300 mg orally, heparin iv to maintain an activated clotting time of >250 sec, and abciximab, as a 0.25 mg/Kg bolus and 0.125 ug/Kg min iv infusion, immediately before the revascularization and continued for 12 hr. Primary PCI was performed according to standard clinical practice using femoral artery Judkins approach via seven French sheath insertion in the right groin. Patients were randomly assigned in a 1:1 manner to intracoronary aspiration thrombectomy using DI or EM before stent placement. After crossing the target occlusive lesión with the guide wire, two or more passages across the lesion from proximal to distal were performed by slowly advancing the aspiration thrombectomy catheter. Subsequently, additional balloon angioplasty or coronary stenting was performed based on standard practice. Patients subsequently received heparin for 48 hr, aspirin 100 mg daily, and clopidogrel (300 mg loading dose, followed by 75 mg/day for at least 6 months). Other adjunctive pharmacotherapy was administered according to operator discretion.
The primary composite angiographic end-points was the occurrence of post-thrombectomy thrombus score (TS) <> 2, and post-stenting myocardial blush grade (MBG) > 2.
The protocol was accepted by the institutional ethical board and was performed in accordance with institutional guidelines and the declaration of Helsinki. All patients provided written informed consent before entering the study.
Clinical Follow-Up
A clinical follow-up was also performed at 1 and 12 months. We evaluated the occurrence of major adverse cardiac events (MACE) [cardiac death, Q and non-Q wave MI, target vessel revascularization] at 1 and 12 months. We also assessed the incidence of stent thrombosis indicated as "definite”, “probable”, and "possible" according to the Academic Research Consortium (ARC) definition.
Devices Description
The DI catheter (Invatec, Brescia, Italy) consists in a central aspiration lumen running through its full length, a soft, atraumatic tip with multiple side holes communicating with the central lumen, with a distal radiopaque marker band, and a luer lock type hub in the proximal end that connects to a stopcock and a syringe for blood aspiration and clot removal [10].
The EM device (Medtronic, Minneapolis, MN) consists in a dual lumen catheter with distal, atraumatic, radiopaque tip marker, and a proximal luer lock port that connects to a thrombus aspiration syringe.
Angiographic Analysis
Coronary angiograms were analyzed off-line by two expert interventional cardiologists in a blinded manner. The advancement of manual aspiration thrombectomy device was filmed, and quantitative coronary analysis was performed before and after the procedure. TIMI flow grade and MBG were estimated visually [14,15], as previously described. The occurrence of slow flow (TIMI flow grade decreasing from 3 to 2 during the procedure) or no reflow (TIMI flow grade decreasing from 2 or 3 to 0 or 1 during the procedure) was assessed. Thrombus burden at lesion site was graded from 0 to 5 according to the TIMI TS [13]. All data were determined at baseline, after thrombectomy, and at the end of the procedure.
ECG Analysis
All patients underwent a 12-lead ECG at baseline, and 90 min after the procedure. The ST-segment elevation was manually measured 20 ms from the J-point was assessed as previously described. ST-segment resolution was expressed as a percentage of the initial ST-segment and a value >70% was defined as indicative for successful myocardial reperfusion 90 min after the Índex procedure (16).
Statistical Analysis
The number of patients included in this study was based on the estimation of the sample size needed to identify a statistically significant difference of the primary end-points in the two groups (17). We estimated that 45 patients would be required in each study group to have a power of 80% to detect an absolute difference in the occurrence of post-thrombectomy TS <> 2 of 30% with a two-sided alpha value of 0.05. All analyses were performed according to the intention-to-treat. Categorical variables are expressed as number of subjects and percentages and are analyzed by the chi-square or Fisher exact test, as appropriate. All continuous variables are expressed as mean ± SD and are analysed by the Student t-test. Differences were considered significant for P value < 0.05.
Multivariate linear regression analysis including clinical and angiographic variables was performed to identify independent predictors of post-thrombectomy TS <> 2. Statistical analysis was performed with StatView, version 5.0 (SAS Institute, Cary, North Carolina).
RESULTS
Baseline Characteristics
One hundred and three consecutive STEMI patients (64.3 ± 10.2 years, 85 males) have been enrolled into this study. Thrombectomy was performed with DI in 52 patients and with EM in 51 patients. All patients underwent stent implantation on the culprit lesion after aspiration thrombectomy. Three patients were not eligible because the vessel reference diameter was <2.5 mm and have been excluded from the study.
Baseline clinical and angiographic Characteristics were similar between the two groups (Tables I and II).
Angiographic and Periprocedural Findings
After manual thrombectomy, EM group showed a significantly lower TS (1.27 ± 0.82 vs. 2.15 ± 0.75, P < p =" 0.016)" p =" 0.009)" p =" 0.009)." p =" 0.0052)"> 2 was significantly higher in EM group (69.3 vs. 92.2%, P = 0.0052) (Fig. 1). Patients treated with EM had a significantly lower incidence of TIMI I (5.8 vs. 30.7%, P = 0.0017), and a higher TIMI 3 flow (72.6 vs. 30.7%, P < 0.0001). Other post-thrombectomy procedural and angiographic Characteristics were similar between groups (Table III).
After stent implantation, the rate of MBG > 2 was significantly higher in EM group (88.2 vs. 69.3%, P= 0.029) (Fig. 1). No statistical differences were observed for each MBG. TIMI flow grade and other post-PCI findings, analysed separately.
The mean time between index reperfusion procedure and post-PCI ECG was 103 ± 22 min. In the pre-PCI ECG, mean ST-segment elevation was 26.7 ± 9.1 mV and 6.6 ± 6.4 mV 90 min post-PCI, resulting in 20.1 ± 9.2 mV absolute ST-segment resolution, and a relative resolution of 75.2 ± 17.6%. No statistical differences were observed for the relative ST-segment resolution 90 min after the index procedure (65.4% (DI) vs. 82.3% (EM), P = 0.072). (Table IV).
At the multivariate analysis, including the baseline clinical and angiographic parameters, the only independent predictor of post-thrombectomy TS <> 2 was the randomization to EM (P = 0.03).
p=0.029
* Post-thrombectomy; Post-Stentíng
Fig. 1. Cumulative rates of primary end-point. TIMI, thrombloysis in myocardial infarction; TS, thrombus score; MBG, myocardial blush grade.
Clinical Outcomes
No significative differences were observed in terms of MACE at 1 and 12 months after the index intervention (Table V). During the first month of follow-up, all cardiac deaths occurred during hospitalization because of complications of cardiogenic shock. We observed in DI group two cases of late stent thrombosis, one "definite" and one "possible," respectively (Table V).
Device-Related Adverse Events
There was no substantial difference in delivery between the two devices, requiring adjunctive support techniques or pre-dilatation. No case of acute coronary perforation or other serious device-related adverse events were observed. However, among the EM group, one patient (1.96%) experienced a coronary dissection following the device usage, immediately proximal to the culprit lesion, and successfully treated with stent implantation covering both the dissection and the culprit lesion.DISCUSSION
Primary PCI currently represents the gold-standard treatment strategy in STEMI, being able to reduce morbidity and mortalily [5,18]. Óptimal myocardial tissue reperfusion is a predictor of long-term outcomes, and represents the goal of primary PCI [15,16,19]. The presence of angiographically visible thrombus is associated with the increased incidence of acute and late post-procedure occlusion of the IRA [20,21. During primary PCI, balloon inflation may induce thrombus dislodgment, plaque disruption, and consequently distal microembolization [22]. Distal atherothrombotic material embolization is one of the mechanisms affecting myocardial reperfusion by mechanical capillary obstruction, endothelial dysfunction, and inflammation, and is associated with a poor long-term outcome [19,23]. During primary PCI, the incidence of this no-reflow phenomenon is 5-20% and results in a reduction of benefit of this interventional procedure [24-30]. In addition, because of the limited ability of coronary artery stenting on attenuating this microvascular impairment, mechanical and pharmacologic approaches have been added to conventional PCI. Previous studies have shown that manual aspiration thrombectomy is safe and feasible in selected STEMI patients [31-34]. However, some significant differences are commonly observed between different manual aspiration thrombectomy devices.
The present randomized study shows that manual aspiration thrombectomy with EM compared with DI improves myocardial reperfusion, providing greater epicardial flow, and remove more thrombotic burden in selected STEMI patients.
The significantly greater reduction of the culprit artery's thrombus burden and the significantly higher incidence of post-thrombectomy TS < 2 in patients treated with EM suggest that this device has a greater effectiveness of thrombotic and soft plaque material removal at the lesion site, resulting in an improvement of myocardial early reperfusion in terms of higher rates of post-thrombectomy
TIMI > 2 and post-stenting MBG > 2.
The similar post-stenting TIMI 3 rate between the two groups suggests that the final post-procedure successful epicardial reperfusion is influenced principally by stent implantation, whereas the final post-procedure successful microvascular reperfusion is associated with a better material removal by EM. These findings may be related to the larger distal dual lumen of the EM device providing conduit for aspiration of a greater amount of embolic material, compared with DI.
Study Limitations
This study represents a single-center experience in a limited number of patients and was not powered and designed to test differences in clinical outcomes.
CONCLUSIONS
Manual aspiration thrombectomy represents an adjunct to pharmacotherapy on the prevention of distal embolization of thrombus, preserving microvascular integrity, in selected STEMI patients. EM catheter in patients with STEMI and visible coronary artery thrombus seems to remove more thrombotic burden compared with DI system, providing a greater post-thrombectomy epicardial flow and a better post-stenting microvascular perfusion.
The Effect of Thrombectomy on Myocardial Blush
in Primary Angioplasty: The Randomized Evaluation
of Thrombus Aspiration by Two Thrombectomy Devices
in Acute Myocardiai Infarction (RETAMI) Trial
Background: In patients with ST-segment elevation myocardial infarction (STEMI), primary percutaneous coronary intervention (PCI) may cause thrombus dislodgment lead-ing to microvascular function impairment, which is a negative independent predictor of myocardial function recovery. Compared with conventional stenting, pretreatment with aspiration thrombectomy during primary PCI significantly improves coronary epicardial flow and myocardial tissue perfusion parameters. We sought to evaluate the angio-graphic findings of two different manual aspiration thrombectomy devices (Diver-lnva-tec (DI) and Export-Medtronic (EM)) in STEMI patients undergoing primary angio-plasty. Methods: We randomized 103 STEMI patients referred to our hospital to undergo primary PCI (<12 n =" 52)" n =" 51)">2, and post-stenting myocardial blush grade (MBG) >2 in the two groups. Resulte: Baseline, clinical, and angiographic preprocedural findings did not differ between the two groups. After aspiration thrombectomy, a TS < p =" 0.0052)."> 2 (69.3 vs. 92.2%, P = 0.0052) and post-stenting MBG >2 (88.2 vs. 69.3%, P = 0.029) were significantly higher in EM group. No significative differences were observed in terms of clinical events at 1 and 12 months. Conclusions: In this single-center, prospective, randomized study, a EM use before stenting iñ STEMI patients seems to remove more thrombotic burden compared with DI, providing a greater post-thrombectomy epicardial flow and a better post-stenting microvascular perfusión. > zoos w¡iey-uss, inc.
Key words: primary angioplasty; ST-elevation myocardial infarction; thrombus; manual aspiration thrombectomy
INTRODUCTION
ST-segment elevation myocardial infarction (STEMI) is typically caused by occlusive coronary thrombus formation on an activated atherosclerotic plaque. Percutaneous coronary intervention (PCI) using coronary stent implantation and glycoprotein IlbIIIa inhibitors administration are considered as standard treatments in this setting [1-3], increasing the rate of thrombolysis in myocardial infarction (TIMI) flow grade on the infarctrelated artery [4,5]. However, myocardial tissue reperfusion is often reduced due to the occurrence of distal atherothombotic debris embolization, and this may limit the efficacy of primary PCI [6]. Recent studies suggest that manual aspiration thrombectomy during primary PCI, in patients with intracoronary, angiographically visible thrombus, can prevent distal embolization, improving myocardial perfusión and reducing the incidence of left ventricular remodeling [7-10].
Despite several systems for intracoronary thrombectomy that differ considerably in construction, principies of operation and management have been introduced into the clinical practice with a widespread use in the setting of primary PCI [11], comparative data are still lacking. The aim of the present randomized study was to evaluate the effects of two different manual aspiration thrombectomy devices (Diver-Invatec (DI) and Export-Medtronic (EM)) on angiographic parameters of epicardial flow and myocardial tissue reperfusion in STEMI patients undergoing primary angioplasty.
METHODS
Study Population
Consecutive patients admitted to our department with STEMI between January 2005 and February 2006 to undergo primary PCI have been enrolled in this study. The inclusion criteria were: diagnosis of STEMI (evidence of ischemic chest pain for >30 min and new ST-segment elevation >2 mm in at least two contiguous electrocardiographic leads) within 12 hr from symptoms onset, de novo coronary artery lesion, occluded single native vessel >2.5 mm in diameter, angiographically identifiable thrombus (presence of a filling defect within the coronary lumen surrounded by contrast medium observed in multiple projections, without calcium within the filling defect or persistence of contrast medium within the coronary lumen) [12,13], TIMI flow grade 0-1, and age >18 years.
Main exclusion criteria were: previous PCI on IRA, rescue PCI, previous myocardial infarction (MI) or coronary artery bypass grafting, and current participation in another study.
Study Protocol and Procedure
All patients were pretreated with aspirin 300 mg orally, heparin iv to maintain an activated clotting time of >250 sec, and abciximab, as a 0.25 mg/Kg bolus and 0.125 ug/Kg min iv infusion, immediately before the revascularization and continued for 12 hr. Primary PCI was performed according to standard clinical practice using femoral artery Judkins approach via seven French sheath insertion in the right groin. Patients were randomly assigned in a 1:1 manner to intracoronary aspiration thrombectomy using DI or EM before stent placement. After crossing the target occlusive lesión with the guide wire, two or more passages across the lesion from proximal to distal were performed by slowly advancing the aspiration thrombectomy catheter. Subsequently, additional balloon angioplasty or coronary stenting was performed based on standard practice. Patients subsequently received heparin for 48 hr, aspirin 100 mg daily, and clopidogrel (300 mg loading dose, followed by 75 mg/day for at least 6 months). Other adjunctive pharmacotherapy was administered according to operator discretion.
The primary composite angiographic end-points was the occurrence of post-thrombectomy thrombus score (TS) <> 2, and post-stenting myocardial blush grade (MBG) > 2.
The protocol was accepted by the institutional ethical board and was performed in accordance with institutional guidelines and the declaration of Helsinki. All patients provided written informed consent before entering the study.
Clinical Follow-Up
A clinical follow-up was also performed at 1 and 12 months. We evaluated the occurrence of major adverse cardiac events (MACE) [cardiac death, Q and non-Q wave MI, target vessel revascularization] at 1 and 12 months. We also assessed the incidence of stent thrombosis indicated as "definite”, “probable”, and "possible" according to the Academic Research Consortium (ARC) definition.
Devices Description
The DI catheter (Invatec, Brescia, Italy) consists in a central aspiration lumen running through its full length, a soft, atraumatic tip with multiple side holes communicating with the central lumen, with a distal radiopaque marker band, and a luer lock type hub in the proximal end that connects to a stopcock and a syringe for blood aspiration and clot removal [10].
The EM device (Medtronic, Minneapolis, MN) consists in a dual lumen catheter with distal, atraumatic, radiopaque tip marker, and a proximal luer lock port that connects to a thrombus aspiration syringe.
Angiographic Analysis
Coronary angiograms were analyzed off-line by two expert interventional cardiologists in a blinded manner. The advancement of manual aspiration thrombectomy device was filmed, and quantitative coronary analysis was performed before and after the procedure. TIMI flow grade and MBG were estimated visually [14,15], as previously described. The occurrence of slow flow (TIMI flow grade decreasing from 3 to 2 during the procedure) or no reflow (TIMI flow grade decreasing from 2 or 3 to 0 or 1 during the procedure) was assessed. Thrombus burden at lesion site was graded from 0 to 5 according to the TIMI TS [13]. All data were determined at baseline, after thrombectomy, and at the end of the procedure.
ECG Analysis
All patients underwent a 12-lead ECG at baseline, and 90 min after the procedure. The ST-segment elevation was manually measured 20 ms from the J-point was assessed as previously described. ST-segment resolution was expressed as a percentage of the initial ST-segment and a value >70% was defined as indicative for successful myocardial reperfusion 90 min after the Índex procedure (16).
Statistical Analysis
The number of patients included in this study was based on the estimation of the sample size needed to identify a statistically significant difference of the primary end-points in the two groups (17). We estimated that 45 patients would be required in each study group to have a power of 80% to detect an absolute difference in the occurrence of post-thrombectomy TS <> 2 of 30% with a two-sided alpha value of 0.05. All analyses were performed according to the intention-to-treat. Categorical variables are expressed as number of subjects and percentages and are analyzed by the chi-square or Fisher exact test, as appropriate. All continuous variables are expressed as mean ± SD and are analysed by the Student t-test. Differences were considered significant for P value < 0.05.
Multivariate linear regression analysis including clinical and angiographic variables was performed to identify independent predictors of post-thrombectomy TS <> 2. Statistical analysis was performed with StatView, version 5.0 (SAS Institute, Cary, North Carolina).
RESULTS
Baseline Characteristics
One hundred and three consecutive STEMI patients (64.3 ± 10.2 years, 85 males) have been enrolled into this study. Thrombectomy was performed with DI in 52 patients and with EM in 51 patients. All patients underwent stent implantation on the culprit lesion after aspiration thrombectomy. Three patients were not eligible because the vessel reference diameter was <2.5 mm and have been excluded from the study.
Baseline clinical and angiographic Characteristics were similar between the two groups (Tables I and II).
Angiographic and Periprocedural Findings
After manual thrombectomy, EM group showed a significantly lower TS (1.27 ± 0.82 vs. 2.15 ± 0.75, P < p =" 0.016)" p =" 0.009)" p =" 0.009)." p =" 0.0052)"> 2 was significantly higher in EM group (69.3 vs. 92.2%, P = 0.0052) (Fig. 1). Patients treated with EM had a significantly lower incidence of TIMI I (5.8 vs. 30.7%, P = 0.0017), and a higher TIMI 3 flow (72.6 vs. 30.7%, P < 0.0001). Other post-thrombectomy procedural and angiographic Characteristics were similar between groups (Table III).
After stent implantation, the rate of MBG > 2 was significantly higher in EM group (88.2 vs. 69.3%, P= 0.029) (Fig. 1). No statistical differences were observed for each MBG. TIMI flow grade and other post-PCI findings, analysed separately.
The mean time between index reperfusion procedure and post-PCI ECG was 103 ± 22 min. In the pre-PCI ECG, mean ST-segment elevation was 26.7 ± 9.1 mV and 6.6 ± 6.4 mV 90 min post-PCI, resulting in 20.1 ± 9.2 mV absolute ST-segment resolution, and a relative resolution of 75.2 ± 17.6%. No statistical differences were observed for the relative ST-segment resolution 90 min after the index procedure (65.4% (DI) vs. 82.3% (EM), P = 0.072). (Table IV).
At the multivariate analysis, including the baseline clinical and angiographic parameters, the only independent predictor of post-thrombectomy TS <> 2 was the randomization to EM (P = 0.03).
p=0.029
* Post-thrombectomy; Post-Stentíng
Fig. 1. Cumulative rates of primary end-point. TIMI, thrombloysis in myocardial infarction; TS, thrombus score; MBG, myocardial blush grade.
Clinical Outcomes
No significative differences were observed in terms of MACE at 1 and 12 months after the index intervention (Table V). During the first month of follow-up, all cardiac deaths occurred during hospitalization because of complications of cardiogenic shock. We observed in DI group two cases of late stent thrombosis, one "definite" and one "possible," respectively (Table V).
Device-Related Adverse Events
There was no substantial difference in delivery between the two devices, requiring adjunctive support techniques or pre-dilatation. No case of acute coronary perforation or other serious device-related adverse events were observed. However, among the EM group, one patient (1.96%) experienced a coronary dissection following the device usage, immediately proximal to the culprit lesion, and successfully treated with stent implantation covering both the dissection and the culprit lesion.DISCUSSION
Primary PCI currently represents the gold-standard treatment strategy in STEMI, being able to reduce morbidity and mortalily [5,18]. Óptimal myocardial tissue reperfusion is a predictor of long-term outcomes, and represents the goal of primary PCI [15,16,19]. The presence of angiographically visible thrombus is associated with the increased incidence of acute and late post-procedure occlusion of the IRA [20,21. During primary PCI, balloon inflation may induce thrombus dislodgment, plaque disruption, and consequently distal microembolization [22]. Distal atherothrombotic material embolization is one of the mechanisms affecting myocardial reperfusion by mechanical capillary obstruction, endothelial dysfunction, and inflammation, and is associated with a poor long-term outcome [19,23]. During primary PCI, the incidence of this no-reflow phenomenon is 5-20% and results in a reduction of benefit of this interventional procedure [24-30]. In addition, because of the limited ability of coronary artery stenting on attenuating this microvascular impairment, mechanical and pharmacologic approaches have been added to conventional PCI. Previous studies have shown that manual aspiration thrombectomy is safe and feasible in selected STEMI patients [31-34]. However, some significant differences are commonly observed between different manual aspiration thrombectomy devices.
The present randomized study shows that manual aspiration thrombectomy with EM compared with DI improves myocardial reperfusion, providing greater epicardial flow, and remove more thrombotic burden in selected STEMI patients.
The significantly greater reduction of the culprit artery's thrombus burden and the significantly higher incidence of post-thrombectomy TS < 2 in patients treated with EM suggest that this device has a greater effectiveness of thrombotic and soft plaque material removal at the lesion site, resulting in an improvement of myocardial early reperfusion in terms of higher rates of post-thrombectomy
TIMI > 2 and post-stenting MBG > 2.
The similar post-stenting TIMI 3 rate between the two groups suggests that the final post-procedure successful epicardial reperfusion is influenced principally by stent implantation, whereas the final post-procedure successful microvascular reperfusion is associated with a better material removal by EM. These findings may be related to the larger distal dual lumen of the EM device providing conduit for aspiration of a greater amount of embolic material, compared with DI.
Study Limitations
This study represents a single-center experience in a limited number of patients and was not powered and designed to test differences in clinical outcomes.
CONCLUSIONS
Manual aspiration thrombectomy represents an adjunct to pharmacotherapy on the prevention of distal embolization of thrombus, preserving microvascular integrity, in selected STEMI patients. EM catheter in patients with STEMI and visible coronary artery thrombus seems to remove more thrombotic burden compared with DI system, providing a greater post-thrombectomy epicardial flow and a better post-stenting microvascular perfusion.
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