Extraction of Challenging Intracoronary Thrombi: Multi-Device Strategies Using Guide Catheters, Distal Vascular Protection Devic

ABSTRACT: Patients with large intracoronary thrombi represent a difficult management problem for the interventional cardiologist. We report 10 cases of challenging thrombi treated percutaneously using varying combinations of deep guide catheter engagement, guide aspiration, dedicated catheter aspiration and withdrawal of a distal filter vascular protection device. These cases demonstrate interventional options which may be considered for such patients.

J INVASIVE CARDIOL 2008;20:455–462

Key Words: coronary; thrombus; embolism; angioplasty; stent;
extraction; distal protection; filter


Management of patients with extensive intracoronary thrombi remains a frontier of interventional cardiology. An initial conservative strategy with antiplatelet and antithrombin medications is often associated with partial or complete angiographic thrombus resolution over subsequent days or weeks.1,2 However, such an approach is not always possible or successful. Most interventional cardiologists are familiar with the daunting scenario of a patient with an acute inferior infarct, an occluded large-caliber right coronary artery, and initial predilatation restoring sufficient flow to reveal a massive thrombus filling much of the distal arterial bed. Devices designed to extract thrombi range from relatively simple hollow tubes with vacuum suction such as Export (Medtronic, Inc., Minneapolis, Minnesota), Rescue (Boston Scientific Corp., Natick, Masssachusetts), and Diver (Avantec Vascular Corp., Sunnyvale, California), to more complex catheter devices such as the XSizer (EndiCor Medical, Inc., San Clemente, California) and the Angiojet (Possis Medical, Inc., Minneapolis, Minnesota). Studies of their routine use in ST-elevation myocardial infarction (STEMI) have yielded mixed results.3–10 These devices may not be able to completely aspirate large or organized thrombi. Nevertheless, we describe a number of approaches to extracting very extensive or otherwise challenging intracoronary thrombi using a combination of devices including the guide catheter, distal protection devices and dedicated thrombus aspiration catheters.

Case Series

Ten native vessel percutaneous coronary intervention (PCI) cases undertaken by the Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand, over the last 4 years are reported. Patients were included if they had extensive intracoronary thrombus (> 15 mm length), or thrombus involving a challenging position such as the left main coronary artery.

The case features are summarized in Table 1. All had acute coronary syndromes. Most were presumed secondary to atherosclerotic plaque rupture, apart from two (Cases 6 and 10) which appeared to be embolic from mechanical prosthetic heart valves. Cases 1–6 all involved extensive right coronary artery (RCA) thrombus managed by deep guide catheter engagement and FilterWire (Boston Scientific Corp., Natick, Massachusetts) withdrawal. Cases 7–10 were left coronary lesions managed in varying ways.

Case 1. A 73-year-old male with a history of hypertension and chronic atrial fibrillation was admitted with a late presentation acute inferior ST-elevation myocardial infarction (STEMI) complicated by pulmonary edema. Coronary angiography documented no significant disease in the left coronary system and an occluded mid-RCA with angiographic thrombus. Using a 6 Fr JR4 guide catheter, the lesion was crossed with a Balance wire and predilatation was performed with a 2.0 mm balloon. A FilterWire EZ was deployed in the distal vessel just proximal to the crux and intracoronary eptifibatide was administered. Dilatation with a 3.0 mm balloon revealed thrombus throughout the distal RCA with TIMI 1 flow (Figure 1A). A 4.0 x 32 mm bare-metal stent was deployed in the mid-to-distal vessel. An angiogram showed some improvement of flow, with significant residual thrombus. The guide was then deeply engaged into the distal vessel and the filter withdrawn (Figure 1B). Aspiration through the guide (Figure 1C) recovered a thrombus of about 12 mm length. Angiography showed a residual stenosis in the distal vessel with evidence of further thrombus. The FilterWire was advanced again and deployed in the posterolateral branch. Two further stents were deployed in the distal RCA. The FilterWire was retrieved and contained significant debris. The final flow was TIMI 3 with no evidence of residual thrombus (Figure 1D).

One day post procedure, the patient developed dysarthria, which resolved over the next 48 hours. A magnetic resonance image (MRI) of the brain showed a small right posterior frontal infarction.

Case 2. A 44-year-old hypertensive male was admitted with a late presentation inferior STEMI. Two days after admission, he developed further chest pain with recurrent inferior ST-elevation. Angiography showed a critical proximal RCA lesion with thrombus extending from the lesion distally into both the posterior descending and posterolateral branches (Figure 2A). There was no significant disease in the left coronary system. Using an 8 Fr guide catheter, a FilterWire EX was advanced into the posterior descending branch and a series of passes was made with a Rescue catheter. There was still extensive thrombus within the vessel. A bare-metal stent was positioned and deployed at the site of the stenosis. The FilterWire was withdrawn expanded from both the distal posterior descending and the distal posterolateral branch of the RCA back to the proximal vessel, during both a Rescue catheter and guide catheter aspiration (Figure 2B). Subsequent angiography revealed a mild residual lesion with some irregularity. This was postdilatated with a 5 mm balloon resulting in a good angiographic appearance (Figure 2C). A large amount of thrombus was aspirated from the guide catheter. Debris was also caught in the FilterWire and aspirated by the Export catheter (Figure 2D).

Case 3. A 50-year-old hypertensive male was admitted with an acute inferior STEMI complicated by bradycardia. He was transferred for angiography, which documented mild left coronary disease and an occluded dominant mid-RCA (Figure 3A). A 5 Fr pacing wire was advanced to the right ventricular apex via the right femoral vein. Primary PCI was performed via a 6 Fr JR4 guide catheter using a Traverse guidewire and predilatation with a 2.5 mm balloon. Restoration of distal flow demonstrated thrombus filling most of the distal RCA and into the right posterolateral branch (Figure 3B). A FilterWire was positioned distally and intracoronary eptifibatide was administered. After further predilatation with a 3.5 mm balloon, a combination technique of withdrawing the expanded FilterWire and advancing the guide catheter, with guide catheter aspiration, was used (Figure 3C). Subsequent angiography showed considerable improvement in the amount of thrombus in the vessel (Figure 3D). The FilterWire was removed, thrombus was extracted from the filter and the device was repositioned in the distal RCA. The 4.0 x 28 mm bare-metal stent was deployed and its proximal portion postdilatated with a 4.5 mm balloon, resulting in a satisfactory angiographic appearance with good distal flow (Figure 3E). A moderate amount of debris was caught in the FilterWire and a large amount of debris aspirated through the guide catheter (Figure 3F).

Case 4. A 39-year-old male was admitted with an inferior STEMI. Initial coronary angiography documented mild left coronary disease and an occluded ectatic, large-caliber RCA (Figure 4A). Predilatation performed with a 2.5 mm balloon revealed extensive thrombus in the distal vessel. A FilterWire was positioned distally (Figure 4B). Deployment of a 4.0 x 38 mm bare-metal stent resulted in marked slow reflow (Figure 4C), despite intracoronary eptifibatide. The guide catheter was advanced through the stent into the distal vessel for thrombus extraction (Figure 4D). A small amount of thrombus was aspirated through the guide catheter and a large amount obtained in the FilterWire. Angiography after multiple intracoronary boluses of nitroglycerin and verapamil showed excellent results (Figure 4E).

Case 5. A 52-year-old male was admitted with a non-STEMI. Angiography showed an occluded mid-RCA with a massive amount of thrombus. A combination of deep engagement of the 6 Fr JR4 guide catheter to the mid-vessel, withdrawal of the expanded FilterWire distal protection device and aspiration into the guide catheter lumen was performed. A large amount of thrombotic debris was aspirated and captured in the filter basket. The artery was then stented, resulting in a good outcome.

Case 6. A 66-year-old female with a history of rheumatic heart disease, chronic atrial fibrillation and ATS mitral and aortic prosthetic valves presented with an acute inferior STEMI. Her prothrombin international normalized ratio (INR) was 2.5 at presentation. Preliminary angiography revealed a thrombotic mid-RCA occlusion and a normal left coronary artery. No improvement of coronary flow was achieved after performing multiple balloon dilatations. Thus, a combination of deep engagement of the 6 Fr JR4 guide catheter to the crux, with withdrawal of an expanded FilterWire distal protection device and aspiration into the guide catheter lumen was performed. After three passes, complete evacuation of thrombus from the vessel was achieved, with relief of chest pain and ST-segment resolution. No atherosclerotic lesion was identified; coronary embolism was considered the most likely diagnosis. A large amount of thrombotic debris was aspirated and captured in the FilterWire. The remainder of her hospital admission was uneventful.

Case 7. A 44-year-old male 3 years post coronary artery bypass surgery was admitted with an acute non-STEMI. He had a left internal mammary artery (LIMA) graft to the LAD and saphenous vein grafts to his mid-obtuse marginal and posterior descending arteries. He continued to smoke and was poorly compliant with his medications. Angiography showed a significant distal left main lesion with associated thrombus (Figure 5A). The area supplied by the proximal part of LAD was not revascularized by the LIMA, so it was elected to treat this percutaneously. The left main stem was engaged with a 6 Fr XB 3.5 guide catheter and a FilterWire EZ was positioned in the downstream LAD. Predilatation was performed using a 2.5 mm balloon. Angiography showed persisting thrombus with extension into the ostium of the circumflex artery. In view of this, the guide catheter was wedged into the left main lesion, which caused pressure damping (Figure 5B), and 30 cc of blood was aspirated. This completely removed the thrombus (Figure 5C). A 3.0 x 16 mm drug-eluting stent (Taxus Express2, Boston Scientific Corp.) was deployed in the left main/LAD and was postdilatated with a 3.5 mm balloon. Subsequent angiography revealed excellent appearances (Figure 5D). A small amount of debris was caught in the filter and a large amount was aspirated through the guide catheter.

Case 8. A 46-year-old male was admitted with a non-STEMI. Angiography showed a critical stenosis with thrombus at the ostium of the LAD (Figure 6A). The thrombus involved the bifurcation of the LAD with the major diagonal branch and appeared likely to embolize down one or both of these arteries. An 8 Fr XB 3.0 guide catheter was shortened by cutting off the proximal 15 cm and attaching a plastic luer-lock adapter (Cook, Inc., Bloomington, Indiana). It was used to engage the left main coronary and a standard-length 5 Fr JR4 guide catheter was advanced through the 8 Fr guide and wedged into the lesion (Figure 6B). The thrombus was aspirated through the 5 Fr guide (Figure 6C) and the lesion was successfully stented (Figure 6D).

Case 9. A 58-year-old male underwent angiography following late presentation with an anterior STEMI and post-infarct angina. The ostium of the LAD had a critical lesion (Figure 7A), without significant disease elsewhere. The LAD lesion was directly stented with a 4.0 x 8 mm bare-metal stent at 16 atm. Subsequent angiography revealed atheroma/thrombus extrusion extending from the LAD back into the left main and down into the circumflex artery (Figure 7B). There was also an apparent dissection flap in the distal left main artery and proximal LAD. Intracoronary eptifibatide was administered. The system was exchanged for an 8 Fr one, and 2 EX FilterWires were deployed in the LAD and circumflex arteries, respectively. Both FilterWires were withdrawn in their expanded configuration (Figure 7C). This reduced the atheroma/thrombus volume. The dissection flap was managed by simultaneous “kissing”-stent deployment of a 4.0 x 8 mm bare-metal stent in the LAD and a 3.5 x 8 mm bare-metal stent in the circumflex artery. An excellent angiographic outcome was achieved (Figure 7D). Significant debris was captured in both FilterWires (Figure 7E).

Case 10. A 57-year-old female presented with an acute inferior STEMI 2 years after a mechanical prosthetic aortic valve replacement for symptomatic severe aortic stenosis. Her INR had been subtherapeutic. Initial angiography documented a large left dominant circumflex vessel with an extensive thrombus, which was likely embolic from her prosthetic valve (Figure 8A). A FilterWire was advanced into the major obtuse marginal vessel and used as an extraction catheter retrieving a large amount of thrombus (Figure 8B). Some thrombus was displaced into the distal circumflex system. The FilterWire was repositioned in this vessel, but despite several extraction attempts, only a small additional amount of thrombus was removed (Figure 8C). The Rescue catheter was then advanced down that vessel and retrieved a small amount of thrombus. With the FilterWire in position, a 3.5 x 24 mm bare-metal stent was deployed. Subsequent angiography showed an excellent appearance (Figure 8D).

Discussion

The presence of any angiographic thrombus predicts both increased distal embolism and increased periprocedural complications in patients undergoing PCI.11–14 The challenges and procedural risks are greater when the thrombus is massive or in a threatening position, such as the left main coronary artery. These cases demonstrate a number of approaches that may be employed to extract challenging thrombi, with the various techniques matched to the particular coronary lesions (Table 2).
Guide catheter aspiration was first described with 9 Fr catheters in the late 1980s,15 with occasional case reports since then.16–18 Current-generation 5 and 6 Fr guides are very useful for extracting large thrombi, as their inner lumen is considerably larger than that of dedicated aspiration catheters. Aspiration lumen caliber strongly predicts thrombus removal efficacy in bench testing.19 Unlike earlier-generation guide catheters, 5 and 6 Fr guide catheters with a reasonably straight configuration, such as the JR4, RCB or multipurpose, can be advanced over a guidewire down many native RCAs (and vein grafts), often as far as the crux. Apart from facilitating thrombus aspiration, very deep engagement of the coronary artery lessens the chance of accidental dislodgement of thrombus into the aorta.

Guide catheters with left coronary shapes can be used to aspirate thrombus from the left main coronary artery, but are less easy to advance over a guidewire down the LAD or circumflex arteries. In the LAD, we used a shortened 8 Fr guide catheter to engage the left coronary ostium with a straightened 5 Fr guide advanced through the 8 Fr guide and down the coronary artery. If a suitable 5 Fr shape is unavailable, a heat gun can be used to straighten any preshaped guide catheter.

Thrombus often propagates distally from a severe lesion. Dilatation of the lesion may be necessary to advance the guide or other aspiration catheter. We found it useful on occasion to dilate the lesion only sufficiently to “wedge” the guide catheter in it, thereby maximizing the suction applied downstream to extract thrombus in a manner akin to proximal occlusion vascular protection devices.

The use of a vascular protection device deployed in the distal coronary artery and withdrawn to the proximal vessel to retract thrombus has been previously reported.20,21 With massive thrombi, this maneuver is associated with a risk of aortic thromboembolism. We combined thrombus retraction with very deep guide engagement and continuous aspiration once the thrombus neared the tip of the guide catheter to minimize the risk of thrombus dislodgement into the aorta.

With very large thrombi, it is important not to extrude the thrombus through the filter when retrieving it. We used two approaches: one was to advance the retrieval catheter far enough to close only the mouth of the filter; the other was not to use a retrieval catheter at all, but rather, withdraw the expanded filter through the deeply engaged guide catheter under constant aspiration. The deployed filter also acts as a “catcher” for thrombus or atheromatous debris dislodged distally during maneuvers such as deep guide engagement. When thrombi extend into more than one distal branch, the filter can be positioned distally in one branch, deployed, withdrawn and closed, and the procedure repeated in the other branch or branches.

The management of these types of thrombi, at the most difficult end of the spectrum, is unlikely to be the subject of a randomized trial. The routine use of either balloon occlusion22 or filter23 distal vascular protection devices during primary PCI for STEMI has not been shown to reduce infarct size; however, patients with a massive thrombus burden were not randomized in these studies.

The data on adjunctive pharmacotherapy in this setting are also limited. There is some evidence that “rescue” use of glycoprotein (GP) IIb/IIIa inhibitors in patients developing intracoronary thrombus might be of benefit.24 All patients in our series were given GP IIb/IIIa inhibitors, mostly eptafibatide, except when thrombolysis had been recently administered. Various intracoronary vasodilators (verapamil, nicardipine, glyceryl trinitrate [GTN], nitroprusside and adenosine, to name a few) have been used in this setting. At our institution, multiple doses of GTN are routinely used during all PCIs; patients with impaired flow receive verapamil and nitroprusside. These agents are believed to help treat concomitant microvascular spasm that often contributes to impaired flow (except for GTN, which is not an arteriolar vasodilator, but rather has effect on the epicardial vessels). Only 1 patient in this series (Case 4) had diminished post-PCI TIMI flow and required such treatment.

Finally, some of these procedures are not without their risks. Deep guide seating may lead to endothelial injury and/or vessel dissection. Similarly, withdrawal of a deployed filter device may cause vessel trauma or result in debris embolization. The use of more than one filter may, in theory, be associated with wire wrapping and difficulty with device capture and retrieval. Careful catheter/device manipulation is always warranted, and multiple final views need to be taken (with or without PCI) if there are any concerns regarding vessel wall integrity.

Study limitations. This case series reflects our recent experience with challenging thrombi. Although the outcomes were satisfactory, it is impossible to be sure whether similar or better outcomes might have been achieved with other approaches. For example, proximal vascular occlusion devices such as the Proxis (St. Jude Medical, Inc., St. Paul, Minnesota) or FAST-LVG (Genesis Medical, Inc., Pittsburgh, Pennsylvania) hold considerable promise for thrombus extraction; aspiration through these devices can be used in combination with filter retraction. We used a dedicated aspiration catheter (the Rescue catheter) as part of the thrombus aspiration strategy in only 2 cases. It is unclear whether other aspiration catheters would have worked as well or better. Blush scores were not systematically documented; however, all but 1 patient had TIMI 3 flow at the end of their procedure. As cardiac biomarkers were elevated prior to intervention, postprocedural changes in creatine kinase or troponin-T were difficult to evaluate. No patient had an obvious procedure-related further elevation. The 1 patient who had a temporary neurologic event first developed signs 24 hours post procedure; the relationship of the event to the procedure is uncertain.

Finally, we would like to highlight that these cases represent several techniques we have been using with variations according to individual patients and operator skill and preference. Whereas they broadly revolve around two methods of thrombus removal (namely aspiration and filter extraction or a combination of both), it should be emphasized that they are by no means standardized approaches. Their application should be guided by the operator’s experience and level of confidence in executing whichever hybrid approach is chosen for the treatment of a specific lesion.

Summary

A number of approaches to challenging intracoronary thrombi are described. A strategy employing deep guide catheter engagement, guide catheter aspiration and filter withdrawal, with variations thereof, was successful in thrombus aspiration, restoration of coronary flow and achievement of satisfactory angiographic and clinical outcomes. These approaches can be useful for the operator to consider in various scenarios.