Percutaneous Treatment of a Single Saphenous Vein Graft with
Two Different Protection Devices

Although the efficacy of coronary artery bypass graft surgery (CABG) has been enhanced by the widespread use of arterial grafts, the limited number of arterial anastomoses mandates continued heavy reliance on venous conduits. Saphenous vein graft (SVG) degeneration is approximately 7% during the first week and 15–20% during the first year; at 10 years, only 40% of patent grafts are free of significant stenosis.
Due to the increased morbidity and mortality rates following repeated bypass surgeries, percutaneous coronary intervention (PCI) became the preferred therapeutic strategy for many patients with SVG disease.^1,2 It has been reported that approximately 10–15% of the patients who undergo PCI had prior CABG.^3,4
However, the treatment of SVGs with stenting is fraught with high complication rates including periprocedural myocardial infarction (MI), target lesion revascularization and long-term mortality.⁵ By reducing the risk of procedure-related atheroembolism, the use of protection devices has become the standard of care during PCI of diseased SVGs.⁶ Previous studies have shown that both balloon occlusion and aspiration systems (GuardWire, Medtronic AVE, Santa Rosa, California; Proxis, St. Jude Medical, St. Paul, Minnesota), as well as distal filters (FilterWire EZ System, Boston Scientific Corp., Natick, Massachusetts) can significantly reduce the occurrence of angiographic and clinical complication during stent implantation in SVGs.^6–8 However, these devices have inherent technical limitations that can prevent a wider application to all kinds of degenerated lesions. We present a case where we overcame the limitations by utilizing two different types of protection devices (Proxis and FilterWire) in order to treat 2 lesions in the same SVG.

Case Report. The patient is a 70-year-old female who underwent CABG in 1994, receiving a left internal mammary graft (LIMA) to the left anterior descending (LAD) artery and a sequential SVG for a diagonal branch, an intermediate branch and the right coronary artery (RCA). In July 2006 she was admitted to the hospital for non-ST-elevation myocardial infarction (NSTEMI) and stabilized on medical therapy. For the recurrence of angina, she was pretreated with abciximab and underwent cardiac catheterization the following day. Diagnostic cardiac catheterization demonstrated severe three-vessel disease with a LIMA to the LAD and a severely diseased SVG with proximal subocclusion and critical stenosis in the distal part of the limb to the RCA. Figure 1 demonstrates the primary target lesion proximal to the SVG and a secondary target in the distal anastomosis. The patient’s left main artery was subtotally occluded, and the LAD presented an ostial total occlusion and several critical stenoses in the proximal, mid and distal parts of the RCA. Her left ventricular function was 40%. Treatment of the culprit lesion (SVG) presented challenges: filter usage would protect the distal zone during the proximal lesion intervention, but would not offer any protection for the distal lesion. Conversely, based on the proximal lesion’s angiographic characteristics, predilatation, rather than primary stenting, was desirable and the use of a proximal occlusion device would have increased the duration of ischemia with a greater risk of angina and left ventricular dysfunction, although this has not been reported during proximal protection. Therefore, we decided to approach these challenges by using two protection devices. During the first step, a FilterWire was easily passed into the SVG across the proximal target stenosis (Figure 2). Predilatation was performed with a 3.5 x 20 mm Maverick compliant balloon (Boston Scientific) inflated at 14 atm for 8 seconds. An interim angiogram showed thrombolysis in myocardial infarction (TIMI) flow 3. A 4.0 x 12 mm Libertè stent (Boston Scientific) inflated at 16 atm for 10 seconds was successfully deployed. Final TIMI flow 3 was achieved. The procedure was completed by treating the distal lesion using the Proxis proximal occlusion device. After device deployment, a 3.5 x 20 mm mm Libertè stent was implanted at 10 atm. Postdilatation with a 3.5 x 18 mm noncompliant balloon (Powersail, Guidant Corp., Santa Clara, California) was performed (Figure 3). Abciximab infusion was started again during the procedure and maintained for a further 12 hours.

The remainder of the patient’s hospital course was uneventful. She was asymptomatic and there was no elevation in postinterventional CK-MB and troponin. The patient remained asymptomatic at 1-month follow up.

Discussion. Because of the softer, more friable atheroma present in vein grafts, the larger size of vein atheroma, and the frequency of associated thrombus formation, coronary embolization is a more common complication during vein graft intervention and the consequences may be serious.⁹
Embolization initiates a complex cascade involving physical capillary obstruction, distal spasm, edema and local thrombosis, all resulting in decreased or absent microvascular flow.^10,11
It has been estimated that periprocedural MI from embolization can occur in up to 20% of cases after SVG PCI. Distal platelet aggregation or mechanical plugging by atheroemboli can be responsible for the “no-reflow” phenomenon, and several studies have shown that it can be associated with worse long-term outcomes. Morishima and associates reported that death at nearly 6 years post procedure was four times more common in patients with angiographic no-reflow than in those with normal flow (37% vs. 10%; p = 0.002).¹² The SAFER and FIRE^6,7 trials have established the efficacy of distal balloon occlusive devices and filter-based protection devices in reducing atherothrombotic debris migration and microvascular impairment during SVG intervention, with a 42% treatment effect. In the SAFER trial, a significant reduction in no-reflow was experienced by patients who underwent PCI using distal protection (3.4% vs, 8.0%; p = 0.026), with a clear reduction in major cardiac adverse ischemic events. Recently, the PROXIMAL⁸ study has shown noninferiority of a proximal occlusion balloon device to a distal one in graft treatment. Mid-term follow-up studies have shown that periprocedural MI is strongly correlated with a reduction in the incidence of repeat out-of-hospital target vessel revascularization (TVR), and even if the mortality rate at 6-month follow up remained high in previous studies, it is reasonable to assume that longer-term follow up will show improvement in the survival curves.
This is believed to be the first report of a procedure carried out with two different protection devices in order to treat two different points of the same diseased SVG. As previously mentioned, filter-based protection devices are not suitable for all types of lesions. They are larger in profile than occlusive devices and need a loop deployment of > 2.5 mm from the lesion to the distal anastomosis, > 2.0 mm in a straight segment and > 1.5 mm from the lesion to the proximal marker,with a recommended vessel diameter of 3.5–5.5 mm. In addition, this device may not capture all debris, it may cause embolization with delivery and it can be occluded by a large burden of atherothrombotic material, with reduced flow or no-flow. Conversely, the proximal occlusion device can be deployed easily, even in a more distal lesion. However, visualization of the anatomy may be difficult, it may not always be possible to achieve complete aspiration, and complete balloon apposition is sometimes not possible.
It has been reported that a large number of lesion types exist with angiographic characteristics that preclude the effective use of distal protection devices. At least one exclusion criteria for the use of distal balloon occlusion devices exists in 57% of vein grafts, and up to 42% of vein grafts have one or more exclusions for the use of a filter device.¹³ In contrast, as many as 18% of patients requiring SVG stenting are not suitable for proximal embolic protection devices by virtue of their lesion location, as the lesion should be > 15 mm distal to the proximal anastomosis.⁸ Previous studies have shown that approximately 35% of all SVG stenoses occur at the proximal anastomosis, 38% in the shaft and 27% at the distal anastomosis.^8–13 Instead of being time-consuming, the use of two different systems, as in the case discussed here, can offer optimal protection for each kind of lesion and enables the operator to obtain a good final result, especially in patients at higher risk of compromised left ventricular function.
Of considerable interest is whether embolic protection devices are safe and effective, even in the management of patients with restenosis of SVG stent sites. It is true that in native coronary interventions, treatment of in-stent restenotic lesions in SVGs is safer than de novo lesion treatment due to the reduction of “slow/no-reflow” and periprocedural MI (0% vs. 20%; p = 0.02).¹⁴ However, recurrences are common. Dangas et al reported target lesion revascularization in 32% and death in 11% of patients at 1 year. It has yet to be demonstrated whether a combined strategy of drug-eluting stent implantation and embolic protection devices can improve long-term outcomes.¹⁵
A final issue that should be addressed is the use of glycoprotein (GP) IIb/IIIa inhibitors. Subanalysis of the FIRE trial¹⁶ has shown that GP IIb/IIIa usage is more effective in combination with filter wire protection by reducing debris migration during anterograde perfusion. In contrast, use with an occlusion device is expected to be associated with poor prognosis as result of incapacity to affect the mechanical condition created by this kind of system, and more probably as an epiphenomenon of higher-risk patients. However, until now, degenerated SVGs seem to be the only lesion type that fails to benefit from GP IIb/IIIa therapy. When data from 5 large trials (EPIC, EPILOG, EPISTENT, IMPACT II and PURSUIT), with over 600 SVG PCI patients, and data from the Cleveland Clinic registry (278 SVG PCI patients) were analyzed, there was no apparent benefit,^17,18 and a possible trend towards worse outcomes has previously been suggested.19 In the case that we have described, abciximab was initiated before the angiographic evaluation based on the clinical condition of the patient and was maintained after the procedure.
Far from considering the case described here as a routine approach to SVGs lesions, we wanted only to provide a possible solution to more complex cases.

References

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