Successful Aspiration of Occlusive Coronary Thrombus with Intracoronary Aspiration Using the Export‚Ñ¢ Catheter

Percutaneous transluminal coronary angioplasty (PTCA) for unstable angina relieves symptoms and reduces the likelihood of subsequent acute myocardial infarction. However, initial procedural success rates in patients with unstable angina are lower than in those with stable angina. This is postulated to mainly be due to the higher complication rates associated with PTCA procedures in this setting.1 Procedure-related mortality has been reported to range from 0–5.4%, periprocedural myocardial infarction rates range from 0–12% and the need for emergency surgery ranges from 3–13%.2–8 Complications are apparently related to an increased incidence of thrombus and plaque instability.2 In addition, distal embolization of plaque constituents following PTCA and stenting is increasingly recognized as an important potential sequelae.9 Angioplasty of degenerated saphenous vein grafts represents another high-risk group of patients. Repeat bypass surgery carries a higher risk of mortality than the first surgical procedure.10 The mechanical disruption of friable plaque by PTCA leading to complete or partial release of atherosclerotic material increases the risk of distal embolization and may be one of the important causes of lower initial success rate in this patient subgroup.1 In addition, the liberation of these particles during balloon angioplasty and stent implantation is associated with complications, including greater than three-fold increase in creatine kinase (CK-MB) in 17% of patients.11 Angioplasty is associated with increased mortality and the no-reflow phenomenon.12,13 Thrombotic occlusion is commonly present in culprit coronary lesions in patients with acute myocardial infarction (AMI),14 which generally results in worse short- and long-term outcomes following balloon angioplasty compared to a situation where thrombus is absent.15,16 It has been reported that occlusive thrombi in the culprit lesions of patients with AMI are comprised of platelets, fibrin, erythrocytes and leukocytes.17 Generally, the causes of impaired coronary flow following the mechanical dilatation of a coronary stenotic lesion include the preexistent impairment of the vasodilatory response in the microcirculation, a residual conduit obstruction (unappreciated dissections) and the acute attenuation of the microcirculatory vasomotor responses by distal embolization and neurohumoral stimuli.18 Recent reports have highlighted the possible advantages of protection systems such as filters (e.g., Angioguard™) and balloon occlusion systems (e.g., Percusurge™) in reducing embolization risk. The present study describes a technique to treat thrombotic coronary artery occlusion in both native coronaries and saphenous vein grafts presenting with acute myocardial infarction (ST and non-ST segment elevation). We used the Export™ catheter from the Percusurge device system without using the distal balloon inflation to successfully aspirate the occlusive intracoronary thrombus. We describe our experience with ten cases in which Export™ catheter aspiration resulted in successful treatment of total occlusive thrombus in native coronaries and saphenous vein grafts. Methods Ten patients presenting with ST or non-ST segment elevation myocardial infarction evidenced by either electrocardiographic abnormalities or increased cardiac serum markers and transferred for either primary or rescue coronary angioplasty were selected. All patients were given aspirin 325 mg, clopidogrel 300 mg loading dose and heparin 100 U/kg to achieve activated clotting times of 300 seconds. Coronary angiograms revealed total occlusion of the infarct-related vessel with thrombus. A right femoral catheter was upsized to a 7 French (Fr) sheath, and 7 Fr guiding catheters were used to cannulate the infarct-related vessel. Lesions were crossed with a 0.014´´ Luge™ wire (Boston Scientific/Scimed, Inc., Maple Grove, Minnesota) or a 0.014´´ Whisper™ wire (Guidant Corporation, Temecula, California) in all cases. The Export™ aspiration catheter (Medtronic, Inc.), which is a monorail catheter connected to a 20 ml syringe providing a low-pressure vacuum to remove debris and thrombotic material, was passed toward the thrombotic occlusion. Approximately 30–60 ml of blood were aspirated while advancing and pulling back the Export™ catheter through the thrombotic lesion. Fresh clots and atherosclerotic plaque materials were retrieved from the filtered aspirated blood. Repeat angiography demonstrated the resolution of the thrombus and restoration of TIMI II-III flow with precise localization of the occlusive lesion area. The remaining lesion was then stented with good angiographic results. Results The patient and lesion characteristics are shown in Table 1. The technical success rate was 100%. There were no major adverse events related to the device itself. Baseline coronary angiograms revealed 100% occlusion with thrombus in all 10 patients. Five patients had saphenous vein graft (SVG) occlusions (4 patients with SVG to right coronary artery and 1 patient with SVG to left circumflex artery) and 5 patients had native coronary artery occlusion (3 patients with acute inferior wall myocardial infarction with total right coronary artery occlusion and 2 patients with acute anterior wall myocardial infarction with total left anterior descending coronary artery occlusion). All patients had TIMI 0 flow on initial angiogram with no visualization of the distal vessel. Thrombotic material was retrieved from all the culprit vessels using the Export™ catheter and restoring TIMI II-III flow. Distal run-off was observed in all patients immediately after the use of the Export™ catheter aspiration technique. Coronary stents were placed in all culprit lesions and TIMI III flow was achieved. None of these patients developed no-reflow phenomenon. No major adverse cardiac events (death, recurrent myocardial infarction, emergent coronary artery bypass graft surgery) occurred during the hospitalization. Aspirated thrombotic material is shown in Figures 1, 2 and 3. Discussion Studies have shown that embolization of the arterial plaque components occurs during coronary interventions in both native coronary arteries and saphenous vein grafts.19,20 Embolization may be associated with disturbances in coronary flow that can be correlated to adverse cardiac events.21 Various techniques have been suggested to prevent plaque embolization.12,22 Along with the aggressiveness of the revascularization techniques, diffuseness of atherosclerotic disease and acuity of clinical presentation are major predictors of adverse outcomes. Mehran and colleagues23 recently quantified plaque burden using intravascular ultrasound during coronary intervention and correlated it with major adverse cardiac events. The lesion plaque volume was the strongest independent predictor of adverse clinical outcomes. Increased plaque embolization due to larger plaque burdens provides the most cogent explanation for these findings. The subjects in the present study, who all had thrombotic occlusion of a culprit vessel, were at significant risk for embolization. For the various reasons explained above, prevention of distal embolization plays a key role in preventing further cardiac events. In this small series of cases, no patient had major adverse cardiac events and the no-reflow phenomenon was not observed. For the initial experience using this new technique to prevent distal embolization, we did not attempt to establish its superiority to the alternate procedures, such as filters (e.g., Angioguard™), balloon occlusion systems (e.g., Percusurge™) and thrombolysis systems (e.g., Angiojet™). Currently, the Export™ catheter device comes packaged with the distal protection balloon device as part of the Percusurge™ system. The cost of the device therefore represents the cost of the entire system. There are no similar monorail aspiration catheters currently available. The cost is presently comparable to other devices for this purpose (e.g., Angiojet™). The main benefits of this technique are that it is easy to perform, requires little preparation, and does not require blindly placing additional devices beyond the occlusive thrombus. The goal of our study was to demonstrate that a simple system employing an aspiration catheter could be used to remove the thrombus and loose atherosclerotic material from culprit vessels. This can restore normal flow pattern and identify culprit lesions that are amenable to coronary stenting in time. Randomized trials will be required to evaluate the clinical impact of this catheter aspiration technique compared to the conventional distal protection devices and thrombolysis systems in coronary interventions.

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