Abstract: Objective. The objective of this study was to assess the effectiveness of mechanical thrombectomy using the Aspire mechanical thrombectomy device (Control Medical) for the treatment of acute myocardial infarction (AMI) as measured by Thrombolysis in Myocardial Infarction (TIMI) flow post procedure compared with baseline. Methods. This is a retrospective study for the treatment of acute myocardial infarction (AMI) in ST-segment elevation myocardial infarction (STEMI) and non-ST segment elevation myocardial infarction (NSTEMI) patients. The study was approved by an independent ethical review board. Data were collected retrospectively from 48 subjects at three study sites. The primary endpoint was TIMI flow post thrombectomy compared with baseline. The safety endpoint was 30-day major adverse cardiac event, defined as death, MI, and target-vessel revascularization (TVR). Eligibility criteria included AMI patients ages 18-90 years who had previous treatment with the Aspire mechanical thrombectomy device, preprocedure TIMI flow 0 to 2, and ability to tolerate antiplatelet therapy. Results. Of the 48 subjects, 81.2% were male, 33.3% were diabetics, 64.6% were hypertensive, 52.1% had hyperlipidemia, and 85.4% had STEMI, with 38.0% anterior and 56.0% inferior AMI. Baseline TIMI flow was 0-1 in 89.6% of subjects. Post-thrombectomy TIMI flow 2-3 was achieved in 85.4% and all subjects had TIMI flow 3 at the end of the intervention. The device did not track in 1 patient and was not used. There were 5 deaths (10.4%), all unrelated to the aspiration thrombectomy procedure, and 0% experienced a stroke. Conclusion. The Aspire mechanical thrombectomy device demonstrated initial effectiveness and safety. Further prospective studies using objective performance criteria to demonstrate effectiveness and safety using the Aspire mechanical thrombectomy device are necessary to determine whether short-term and long-term outcomes improve over previously published clinical trials.
J INVASIVE CARDIOL 2020 February 5 (Epub Ahead of Print).
Key words: AMI, PCI, STEMI, thrombectomy
Thrombectomy devices have been commonly utilized in percutaneous coronary intervention (PCI) of the coronary arteries after ST-segment elevation myocardial infarction (STEMI). The treatment of patients who present with STEMI includes either thrombectomy prior to angioplasty or primary angioplasty alone. It has been shown that thrombus removal by aspiration thrombectomy before stent placement has the potential for reducing distal embolization and improving ST-segment resolution and improving Thrombolysis in Myocardial Infarction (TIMI) flow and microvascular perfusion (myocardial blush scores).1,2
Various tools, including manual thrombectomy and mechanical thrombectomy, are utilized to perform thrombectomy in the coronary arteries. Manual thrombectomy requires devices such as catheters and syringes to aspirate the thrombus. Examples of manual catheters include the Export aspiration catheter (Medtronic) and the QuickCat extraction catheter (Philips). Manual aspiration catheter systems may not provide the desired results. They lose aspiration force as the syringe loses suction. Additionally, the quality of thrombus aspiration is influenced by numerous technical and pathological variables, including the area of the aspiration lumen, the length of the aspiration lumen, the shape of the lumen, the size of the thrombus, viscosity of the aspirant, and the amount of the proximal aspiration force. When removing blood clots, sometimes subtle, low thrombectomy force is needed, while other times continuous force, pulsed force, or increased force is required. Additionally, syringes usually only allow a maximum aspiration volume of 30 mL at a time, requiring repeated catheter removal, disconnection, reconnection, and insertion maneuvers. This increases the length of procedure time and can increase the risk of biohazard exposure to the physician and staff.1
Mechanical thrombectomy devices utilize various mechanisms to perform thrombectomy. Some fragment or macerate the thrombus prior to aspiration, such as the AngioJet Ultra coronary thrombectomy system (Boston Scientific). The AngioJet system is a mechanical thrombectomy device for PCI patients with large thrombus burden utilizing mechanical thrombectomy for removal of thrombus in coronary arteries. The system is designed to mechanically restore blood flow of patients with thrombosed arteries.1 The mechanism of action for the AngioJet system uses high-pressure saline to create a vacuum at the tip of the catheter to break up and remove thrombus. Existing technologies include costly capital equipment with disposable catheters.
Aspiration thrombectomy may be utilized in the treatment of STEMIs, and although studies have shown improved myocardial perfusion and ST-segment resolution, in many studies there have been no differences shown in mortality, reinfarction, death, or target-vessel revascularization (TVR).2-8 Jolly et al reported an increased risk of stroke at 30 days.9 A 2013 meta-analysis by Kumbhani et al10 comprised three studies, including 176 patients treated with the X-sizer (ev3) and 550 patients treated with the AngioJet; they reported that manual aspiration (but not mechanical thrombectomy) was beneficial in reducing major adverse cardiac event (MACE) rate. Alternatively, a 2013 study by Narvese et al11 reported that mechanical thrombectomy might provide a benefit by reducing repeat infarction and stroke compared with manual thrombectomy.
Because multiple studies3,4,9,12 — mostly on manual aspiration of thrombus — failed to show evidence of a long-term benefit from thrombectomy in the STEMI setting, the 2015 American College of Cardiology/American Heart Association/Society for Cardiovascular Angiography and Interventions (ACC/AHA/SCAI) focused update on primary PCI for patients with STEMI13 removed the prior class IIa recommendation for aspiration thrombectomy, with routine aspiration thrombectomy for STEMI no longer recommended. The studies referenced by the ACC/AHA/SCAI team demonstrate that there is a limited availability of effective tools that are easy to use and not cost prohibitive; thus, effective thrombus removal is a primary challenge in the treatment of STEMI patients.
The Aspire mechanical thrombectomy device (Control Medical Technology) is a rapid-exchange mechanical thrombectomy system that removes fresh blood clots and emboli from the coronary and peripheral vasculature (Figure 1). In an in vivo study, the Aspire device removed more thrombus than a 60 mL syringe, which is a standard volume for thrombus removal with one of the multiple catheters that exists on the market today.1 This retrospective study is an initial assessment that focuses on the safety and effectiveness of the Aspire device for the treatment of acute myocardial infarction (AMI).
The objective of this study was to assess the effectiveness of mechanical thrombectomy using the Aspire device as measured by TIMI flow post procedure compared with baseline. Both STEMI and non-STEMI patients were included. The retrospective study protocol was approved by an independent national ethical review board. Data were collected from 48 subjects at three study sites. The primary endpoint of the study was TIMI flow post thrombectomy compared with baseline. The safety endpoint included 30-day MACE rate, with MACE defined as death, MI, and TVR. Eligibility criteria included age >18 years and <90 years; diagnosis of AMI; previous treatment with the Aspire mechanical thrombectomy device; preprocedure TIMI flow 0 to 2; and ability to tolerate antiplatelet therapy.
PCIs included the use of the Aspire device to remove as much of the thrombus burden as possible prior to angioplasty and stenting. All subjects were given routine anticoagulation therapy, such as heparin, bivalirudin, and/or glycoprotein IIb/IIIa inhibitor; choice of antiplatelet therapy was at the physician’s discretion. Post intervention, patients were prescribed aspirin along with either ticagrelor, clopidogrel, or prasugrel.
Each institution followed standard protocol for the diagnosis and treatment of each AMI patient. All subjects were treated with the Aspire thrombectomy device.
The Aspire mechanical thrombectomy device. The Aspire aspirator (Figure 1) is made up of a novel mechanical aspirator, a closed system with integrated drain, and large-lumen aspiration catheters. The device is conﬁgured with handles that create a mechanical advantage to actuate and control the plunger with one hand during aspiration. Squeezing the handles starts, or increases, aspiration, and releasing the handles stops, or slows, aspiration with one hand. This frees up the clinician’s other hand to advance, retract, and manipulate the aspiration catheter in vivo. The system is conﬁgured with a one-way valve on the barrel tip that opens when the handles are squeezed to aspirate and closes when the handles are released. Simultaneously, a one-way valve on the plunger seals during aspiration and opens when the handles are released to drain ﬂuid, air, and/or aspirant in the barrel. The plunger valve connects to an off-the-shelf drain bag to create a closed ﬂuid collection circuit similar to some electromechanical maceration–aspiration systems. A closed ﬂuid system allows 250 mL to be aspirated without multiple catheter disconnections (Figure 2).
The Aspire handles, valves, and closed ﬂuid system combine for improved control during aspiration compared with basic and locking syringes. Squeezing the handles two or more times during aspiration and purging air in the barrel can help the clinician create and maintain continuous aspiration force. Clinicians also pulsed the aspiration force for targeted or spot aspiration by moving the catheter into position without squeezing the handles, positioning the catheter up against a discreet thrombus, and then sequentially squeezing the handles at least two or more times.16
After thrombus aspiration, PCI included angioplasty followed by stenting. Angiograms were de-identified and evaluated by the physicians for this study. TIMI flow was graded according to ACC/AHA Key Data Elements and Definitions for Cardiovascular Endpoint Events. TIMI grade 0 flow is defined as no perfusion and no antegrade flow beyond the point of occlusion. TIMI grade 1 flow is defined as penetration without perfusion — the contrast material passes beyond the area of obstruction but “hangs up” and fails to opacify the entire coronary bed distal to the obstruction for the duration of the cine-angiographic filming sequence. TIMI grade 2 flow is defined as partial perfusion — the contrast material passes across the obstruction and opacifies the coronary bed distal to the obstruction. However, the rate of entry of contrast material into the vessel distal to the obstruction or its rate of clearance from the distal bed (or both) is perceptibly slower than its entry into or clearance from comparable areas not perfused by the previously occluded vessel (eg, the opposite coronary artery or coronary bed proximal to the obstruction). TIMI grade 3 flow is defined as complete perfusion — antegrade flow into the bed distal to the obstruction occurs as promptly as antegrade flow into the bed from the involved bed and is as rapid as clearance from the uninvolved bed in the same vessel or the opposite artery.14,15
Forty-eight patients were treated at three centers from July 2016 through July 2018. Forty patients (80.0%) were male; 17 patients (34%) had diabetes mellitus. The majority had hypertension, and almost half were current smokers. Eighty-six percent of the patients presented with STEMI. Demographic data are presented in Table 1. Baseline stenosis ranged from 80%-100%, with totally occluded culprit vessels in 68.8% of the patients. One subject did not receive aspiration thrombectomy due to inability of the device to track. TIMI 3 flow was achieved in the final result in this patient, and there were no device-related complications.
The angiograms were de-identified and evaluated by all three investigators. In 85% of the patients, TIMI 2 to 3 flow was achieved from the thrombectomy device alone. TIMI 3 flow was achieved in all subjects at the end of the PCI. There were no occurrences of TVR through 30 days. None of the subjects experienced a stroke or a transient ischemic attack. There were no intraprocedural deaths and 5 postprocedural deaths; causes of death were cardiac arrest on the day of the procedure in 1 patient, septic shock and cardiogenic shock at 6 days post procedure in 1 patient, AMI at 7 days post procedure in 1 patient, sepsis at 64 days post procedure in 1 patient, and congestive heart failure at 232 days post procedure (patient in hospice).
The Aspire thrombectomy device was 510(k) cleared for the intended use of aspirating fluids from the body.16,17 The Aspire device did not contribute to any data that led to the change in the most recent ACC/AHA/SCAI focused update on primary PCI for patients presenting with STEMI.13
The Aspire Max aspiration catheters are conﬁgured with large lumens, are aspiration crush-proof, and feature braided kink-resistant shafts. The catheters may be used with or without a guidewire in place. Clinicians may aspirate over-the-wire with the wire in place if a y-adapter or similar proximal accessory is used. Aspiration may also be performed without a wire in place. Over-the-wire aspiration catheters feature up to 50% more aspiration lumen area than comparable rapid-exchange aspiration catheters with the same crossing proﬁle. A larger aspiration area improves aspiration force and speed.1 It should be noted that none of the subjects in this study experienced a stroke, and higher stroke rates have been associated with mechanical thrombectomy for the treatment of AMI.18,19 This small, retrospective study demonstrated initial safety and efficacy.
Study limitations. The limitations of this study were the retrospective design, small sample size, and short-term follow-up. Additionally, it would be beneficial to understand if use of this device minimizes the amount of time required to perform mechanical thrombectomy and the overall procedure time.
In addition to extraction of thrombus at the lesion location, mechanical thrombectomy can be used for retrieval of distal emboli. This is the initial report of outcomes in patients treated with the Aspire thrombectomy device in STEMI and non-STEMI patients. More-effective thrombectomy devices may promote improved long-term outcome, such as reductions in mortality, reinfarction, TVR, and death. Further prospective studies with objective performance criteria to demonstrate the effectiveness and safety of the Aspire device are necessary to determine whether short-term and long-term outcomes improve over previously published clinical trials.
Acknowledgments. The authors would like to acknowledge Eminence Clinical Research, Inc (Colorado Springs, Colorado) for assistance with study management, statistics, and medical writing.
From the 1UNC REX Healthcare, Raleigh, North Carolina; 2Ballad Health, Johnston Memorial Hospital, Abingdon, Virginia; and 3Winter Haven Hospital, Winter Haven, Florida.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.
Manuscript submitted August 26, 2019, provisional acceptance given August 29, 2019, final version accepted September 20, 2019.
Address for correspondence: George L. Adams, MD, MHS, MBA, FACC, FSCAI, 1UNC REX Healthcare, 400 Health Park Drive, Raleigh, NC 27607. Email: George.Adams@unchealth.unc.edu
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- Control Medical, Inc. Instructions for use: 04005-00 Rev A.
- Control Medical Technology 510(k) clearance letter, K131998. November 26, 2013.
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