Distal Protection of the Left Anterior Descending Artery with the EX Filter Wire During an Acute Coronary Syndrome

Distal coronary embolization is an unpredictable complication of percutaneous coronary intervention (PCI). No reflow, distal coronary occlusion and peri-procedural cardiac enzyme elevation (“infarctlets”) may result from distal embolization. Traditional treatment for these phenomena has focused on distal microvasculature vasodilators like nitroprusside, verapamil, and adenosine. Enthusiasm for embolic protection during PCI has increased with studies suggesting lower peri-procedural complications and major adverse cardiac events with their use.^1,2 Thrombus aspirators (TEC, Interventional Technologies, San Diego, Calif.) and Angiojet^® (Possis Medical, Inc., Minneapolis, Minn.), disintegrators (Cordis Hydrolyzer, Acolysis System, Cordis Corp., Miami Lakes, Florida), occlusion-aspiration devices (PercuSurge GuardWire, PercuSurge, Inc., Sunnyvale, Calif.), and most recently, filters (Emboshield, Angioguard, Filter Wire EX), comprise the major classes of distal protection devices.³ In this case report, we desribe the use of the Filter Wire EX in a patient during an acute coronary syndrome. Case report. A 61-year-old Caucasian male with no prior history of CAD presented with 48 hours of unstable angina. Troponin I was elevated. No ischemic changes were present on the EKG. Medical management was instituted with aspirin, beta-blockers, enoxaparin, and eptifibatide. The patient underwent diagnostic angiography and the culprit lesion with a “filling defect” suggestive of intralesional thrombus was identified in the LAD (Figure 1). An EBU 4 Zuma 2 7 Fr guiding catheter (Medtronic AVE, Santa Rosa, Calif.) was used for the intervention. The 0.014 mm EX guardwire (Boston Scientific, Maple Grove, Minn.) was used to cross the lesion and the expandable distal nitinol umbrella was deployed in the mid LAD (Figure 2). A 3.5 x 18 mm Cypher sirolimus stent (Cordis, Johnson & Johnson, Miami, Florida) was primarily deployed at 14 atm to cover the mid-LAD lesion (Figure 3). Final angiographic and clinical results were reassuring (Figure 4). TIMI-3 flow was maintained throughout the procedure and consequently, no peri-procedural intracoronary vasodilators were used. On retrieval of the filter, trapped thrombus and fibrinoid material was seen. The patient had no post-procedural CPK leak and was discharged home the next day uneventfully. Discussion. Clinical studies using thrombectomy and distal protection devices have shown lower periprocedural adverse events in saphenous vein grafts.^1–4 Distal protection device usage in the coronary circulation has been therefore mostly limited to saphenous vein graft interventions.^5,6 Although trials with the thrombus extraction catheter (TEC) were disappointing,³ the Angiojet rheolytic thrombectomy catheter demonstrated a reduction in major adverse cardiac events (MACE) in acute ST segment elevation myocardial infarction patients.⁷ Thrombectomy using the X-sizer catheter was also successful in reducing the thirty day event rate of myocardial infarction and death in both vein grafts and native coronary arteries.⁸ The landmark SAFER trial demonstrated the superiority of stenting with distal protection in vein grafts over stenting without distal protection.⁶ The peri-procedural MI rate was reduced from 17% to 9% in favor of the arm in which the Percusurge Guardwire embolic protection device was used. Some form of distal protection has therefore become standard of care for vein graft interventions today. Filters are the next generation of distal protection devices. Non-inferiority of the EX system with the Percusurge device in vein grafts was demonstrated in the FIRE trial.⁹ Filters are preferred over balloon occlusive devices because of their simplicity of use and their ability to maintain antegrade flow through the vessel. This is important for patients with severe LV dysfunction or patients with a culprit vessel supplying a large myocardial territory. PTCA balloon occlusion in these patients is often not safe or tolerated. The potential drawbacks of any filter system is the potential distal embolization that could occur during the initial passage of the wire and protective sheath across the thrombus laden lesion. One of the lessons learned during the management of saphenous vein graft lesions is that distal embolization is unpredictable and could occur even during treatment of seemingly innocuous lesions. Whether or not distal protection should be used only in native vessels when the thrombus burden is huge and deferred for focal lesions will need to be answered in a randomized trial. This case highlights the successful use of the EX guidewire in the native coronary circulation. Several prerequisites should be fulfilled before the device is used in the native circulation. First, the lesion needs to be accessible. The vessel needs to be of adequate size (at least 3.5 mm) to allow for the safe passage and deployment of the EX Filter wire. The 0.014 inch wire that guides the filter is not as easily maneuverable as the array of versatile standard coronary guide wires. Second, there should be no major branch vessel proximal or within 15 mm distal to the lesion to allow for appropriate placement of the filter wire. Thirdly, there needs to be a straight segment of the vessel distal to the lesion for filter deployment. Lastly, the distal filter must not be moved within the vessel during the more proximal intervention. Incomplete filter apposition, loss of trapped material during retrieval, and distal passage of smaller material remain the limitations of all filter devices. Orthogonal views are recommended to detect filter loop apposition. Minimum lesion to filter distance of 1.5 cm, and 2 cm straight segment are highly recommended. Gentle retraction of the nitinol loop during retrieval is also recommended to prevent loss of thrombus. Conclusions. Once the value of epicardial conduit patency and microvascular integrity becomes more widely accepted, distal protection devices should gain a more prominent role in percutaneous intervention during acute coronary syndromes. This case highlights the successful use of the EX Guidewire to treat a mid-LAD lesion during an acute coronary syndrome. The use of distal protection in settings such as that described in this case report will increase now that the EX filter wire has shown clinical benefit in vein graft intervention. Randomized trials are needed to justify and direct the use of distal protection devices in the native coronary circulation during acute coronary syndromes.

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