Complex SVG PCI in Acute Coronary Syndrome: Case 3 of a 5-part series

Utilization of laser ablation and intragraft glycoprotein IIb/IIIa inhibitors via ClearWay therapeutic infusion catheter to improve procedural safety

We describe a complex thrombotic saphenous vein graft (SVG) percutaneous coronary intervention (PCI) case resolved with the aid of laser atherectomy and ClearWay™ (Atrium Medical Corporation, Hudson, NH) local abciximab delivery. ClearWay is a low-profile, rapid-exchange therapeutic infusion catheter and is indicated for localized perfusion of various diagnostic and therapeutic agents into the coronary and peripheral vasculature. The ClearWay therapeutic infusion catheter enables local drug delivery to reach approximately a 500-fold greater drug concentration versus systemic delivery. The catheter’s novel OCI (occlusion, containment and infusion) therapeutics platform occludes flow temporarily. While the flow is occluded, the thrombus is contained and the drug is infused, maximizing the drug bioavailability at the site and enabling an enhanced therapeutic effect. Note: The September and October 2008 issues of Cath Lab Digest described use of the ClearWay catheter in ST-elevation myocardial infarction cases (available online at www.cathlabdigest.com). Case Report Patient is a 58-year-old male who underwent coronary artery bypass graft surgery (CABG) in 1999 with SVG sequential to obtuse marginal (SVG-OM) x2 and SVG to diagonal branch of the left anterior descending (LAD) artery (SVG-Diag). He presented to Pinnacle Health Institution with acute coronary syndrome. The patient underwent cardiac catheterization which revealed a distal left main 75% stenosis as well as a distal LAD 80% lesion. In addition, he had complex disease of both SVGs with left ventricular (LV) systolic function estimated at 50% by left ventriculography. His SVG-OM had 70% proximal stenosis, 90% mid lesion with filling defect suggestive of large thrombus associated with ruptured plaque, and after first anastomosis, another 80% stenosis (Figures 1-2). The SVG-Diag also had diffuse 75% proximal and mid lesions. It was decided to intervene upon the left main, LAD and SVG-OM branch during index hospitalization. Initially, an 8 French (F) intra-aortic balloon pump (IABP) was placed prophylactically. The left main and LAD were treated with Endeavor drug-eluting stents (Medtronic, Santa Rosa, CA). Then we proceeded with PCI of SVG-OM in the same setting. It was determined that there was no appropriate landing zone for placement of a distal or proximal embolic protection device (EPD). A 8F Hockey-stick (HS) guide catheter was chosen to engage the SVG. The lesions were navigated easily with 0.014-inch Balance Middle Weight (BMW) wire (Abbott Vascular, Redwood City, CA). As a foundation anticoagulant, the patient received intravenous (IV) heparin. Initially, two passes were made with a 1.4 mm laser atherectomy catheter (Figure 3). This improved the lesion severity and allowed placement of a ClearWay 2.0 mm x 20 mm therapeutic infusion catheter in the lesion. Via this catheter, an intra-graft abciximab weight-based bolus was administered, resulting in substantial improvement in thrombus grade and lesion severity (Figures 4-5). Additional laser atherectomy was performed with a 1.7 mm as well as 2.0 mm laser catheter (Figure 6). After re-prepping, the ClearWay catheter was placed in the graft and intra-graft sodium nitroprusside was administered prophylactically to prepare distal microcirculation for stent implantation. From distal to proximal, a 4.0 mm x 28 mm Vision (Abbott Vascular) and 5.0 mm x 28 mm and 4.5 mm x 28 mm Ultra stents (Abbott Vascular) were implanted. Final angiography demonstrated excellent angiographic result with TIMI-3 flow and a myocardial blush grade of three (Figure 7). The patient was discharged 2 days post procedure. He was brought back several weeks later for SVG-Diag PCI, which again was accomplished using an EPD as well as with intra-graft ClearWay-directed delivery of abciximab and DES implantation. The patient remained asymptomatic at follow up with normal left ventricular systolic function. Discussion Saphenous vein graft (SVG) PCI is known to be associated with high risk of no reflow (8-15%)1,2 and periprocedural MI (up to 28%).3,4 This is largely due to a very high incidence of athero-thromboembolism that occurs during SVG PCI. Due to vein graft degeneration, high atheroscelerotic burden with soft plaque and thrombus is the norm. This sets the stage for distal embolization during SVG PCI, ultimately leading to poor outcome. Several embolic protection devices have shown significant improvement in rates of distal embolization and improved procedural safety.4 However, these devices are not universally effective. In embolic protection device (EPD) trials, the major adverse cardiac events (MACE) rate still remains at 10%, which suggests persistent risk of micro-embolic showers occurring despite EPDs, producing myocardial damage.5,6 Furthermore, there are many patients who do not have appropriate distal landing zones for placement of embolic protection devices. One proximal embolic protection device is available in the U.S., but many SVGs have proximal disease and angulation that preclude the use of this device. In addition, certain patients with single remaining grafts and poor LV dysfunction may not tolerate flow occlusion. Also, limitations exist on the size of the devices or stents which can be utilized with this technology. It is well known that glycoprotein IIb/IIIa inhibitors reduce the overall MACE in acute coronary syndrome intervention. Published IV abciximab trials in SVG intervention have not shown to reduce periprocedural events or improve MACE.7 Conversely, a multi-center pilot trial of SVG PCI8 (n = 58), performed using Dispatch catheter-delivered intra-graft abciximab, demonstrated statistically significant median percentage diameter stenosis reduction (69% to 45%, p = .0001), and improvement and reduction in thrombus grade (68% to 34%, p = .0001). In a similar study of SVG PCI,9 use of transluminal extraction coronary (TEC) atherectomy and intra-graft abciximab demonstrated excellent procedural safety with no evidence of embolization or no reflow. This improvement with intra-graft versus IV abciximab can be explained by the in vitro studies, which suggest that achieving 100 times systemic concentration of glycoprotein IIb/IIIa inhibitors leads to thrombo-disaagregation properties.10 Reduction in thrombus burden then reduces likelihood of distal embolization. High local concentration of glycoprotein IIb/IIIa inhibitors can be achieved with ClearWay-directed delivery. This approach should add great value to complex SVG PCI. In our single-center experience, we have seen very promising results with use of intra-graft abciximab delivered via the ClearWay catheter, in conjunction with EPD, mechanical thrombectomy or laser atherectomy. Together, this pharmaco-mechanical approach has produced excellent acute procedural outcomes in very complex, diffusely diseased thrombus containing vein graft PCI. In summary, significant limitations still exist with currently available approaches and further refinement in thrombus management is needed to improve safety and outcome of these complex procedures. As shown in this procedure where neither a proximal nor distal protection device was feasible, use of intra-graft abciximab followed by laser atherectomy allowed safe completion of the PCI procedure. This may be explained with the achievement of higher drug concentrations at the site of thrombus due to utilization of the ClearWay therapeutic infusion balloon catheter, potentially leading to improved efficacy. Rajesh M. Dave, MD, can be contacted at rdintervention@yahoo.com

1. White CJ, Ramee SR, Collins TJ, et al. Percutaneous angioscopy of saphenous vein cononary bypass grafts. J Am Coll Cardiol 1993; 21: 1181-1185.
2. White CJ, Ramee SR, Collins TJ, et al. Coronary thrombi increase PTCA risk. Angioscopy as a clinical tool. Circulation 1996; 93: 253-258.
3. Piana RN, Paik GY, Moscucci M, et al. Incidence and treatment of “no reflow” after percutaneous coronary intervention. Circulation 1994; 89: 2514-2518.
4. Lee CH, Wong HB, Tan HC, et al. Impact of reversibility of no reflow phenomenon on 30-day mortality following percutaneous revascularization for acute myocardial infarction — insights from a 1,328 patient registry. J Interv Cardiol 2005; 18:261-266.
5. Gick M, Jander N, Bestehorn HP, et al. Randomized evaluation of the effects of filter-based distal protection on myocardial perfusion and infarct size after primary percutaneous catheter intervention in myocardial infarction with and without ST-segment elevation. Circulation 2005; 112:1462-1469.
6. Stone GW, Rogers C, Ramee S, et al. Distal filter protection during saphenous vein graft stenting: technical and clinical correlates of efficacy. J Am Coll Cardiol 2002; 40:1882-1888.
7. Roffi M, Mukherjee D, Chew DP, et al. Lack of benefit from intravenous platelet GP IIb/IIIa receptor inhibition as adjunctive treatment for percutaneous interventions of aortocoronary bypass grafts. Circulation 2002; 106:3063-3067.
8. Barsness GW, Buller C, Ohman EM, et al. Reduced thrombus burden with abciximab delivered locally before percutaneous intervention in saphenous vein grafts. Am Heart J 2000; 139(5): 824-829.
9. Sullebarger JT, Dalton RD, Nasser A, et al. Adjunctive abciximab improves outcomes during recanalization of totally occluded saphenous vein grafts using transluminal extraction atherectomy. Catheter Cardiovasc Interv 1999; 46: 107-110.
10. Moser M, Bertram U, Peter K, et al. Abciximab, eptifibatide, and tirofiban exhibit dose-dependent potencies to dissolve platelet aggregates. J Cardiovasc Pharmacol 2003; 41:586-592.