The Unrelenting Challenge of Vein Graft Disease
Despite effective embolic protection devices and drug-eluting stents, saphenous vein graft (SVG) intervention remains technically challenging, and long-term results are discouraging.1 Procedural success and reductions in target lesion revascularization are overshadowed by the relentless failure of the SVG outside the target segment.2 Vein graft disease has a trimodal distribu- tion, early failure within the first 1–2 months due to thrombotic occlusion, mid-term failure in the first 1–3 years as a consequence of intense intimal hyperplasia, and late failure (after 3 years) due to accelerated atherosclerosis.3 Over half of implanted vein grafts are occluded at 10 years post surgery and another quarter have significant obstructions.4 Saphenous vein graft PCI is unlike native vessel intervention. Bulky and friable atheroma, frequently not having a well-developed surface cap, substantially increases the risk of distal embolization. Furthermore, these patients often have higher global atherosclerotic burdens, poorer left ventricular function and a greater number of comorbidities. Without embolic protection, periprocedural myocardial infarction (MI) occurs in 15–35% of patients.5 Hong and colleagues demonstrated that the prognostic consequences of such infarcts are considerable.6 Those patients suffering a periprocedural MI have a mortality of two and half-fold higher at 1 year than those having no MI. Predicting in whom clinically significant distal embolization will occur has been difficult. Studies examining such predictors have demonstrated that SVG degeneration score, the presence of thrombus and the total plaque volume are predictive, although in the individual patient the predictive value of any one of these or a combination is not sufficient to negate the need for embolic protection, a therapy that reduces periprocedural infarction by nearly 50% and the incidence of no reflow by 70%.5,7,8 These compelling data led to embolic protection being a class 1 recommendation during SVG PCI. In spite of the overwhelming evidence of its benefit, embolic protection is employed in the minority of SVG interventions in the United States.9 Abdel-karim and colleagues10 in this issue of the journal add considerably to our understanding of the most difficult of vein graft patients: those presenting with an acute occlusion. Brodie et al have confirmed the poor prognosis in patients presenting with an acute ST-elevation MI from SVG occlusion.11 In the present article, 34 patients with prior bypass surgery underwent 36 PCIs for an occluded SVG graft. Nearly
60% had a non-ST-elevation MI, 22% a ST-elevation AMI and 20% unstable angina. SVG occlusion was due to stent thrombosis in nearly of 40% of the patients. Overall, successful recanalization of the thrombosed graft using a variety of techniques including aspiration and rheolytic thrombectomy and distal and proximal embolic protection was 81%. The 3- year mortality was high, at 42%, as was the incidence of a sub- sequent acute coronary syndrome, 41%, and the need for repeat coronary revascularization, 34%. As noted in the paper, the acute and long-term failure of acutely occluded vein grafts likely results from diffuse, degenerative atherosclerotic disease, the large thrombus burden which is not optimally managed by any individual or any combination of devices today, and associated poor flow from infarction and microvascular dysfunction. All of these may contribute to the high stent thrombosis rate noted in this study.
What are we to do given these data? Unfortunately, when faced with a patient with acute vein graft occlusion, options are limited. Frequently, these patients are not candidates for repeat bypass grafting, and certainly in the setting of STEMI, the time to reperfusion would be inordinate. Often, the best alternative is to avoid the SVG and intervene on the native vessel, an option not frequently available given the long diffuse native-vessel total occlusions that accompany these degenerated grafts. In 2 patients in the current study, the native vessel was recanalized successfully when the SVG PCI failed. When the acutely occluded SVG must be treated, a combination of aggressive thrombectomy and associated embolic protection would seem the best approach, as outlined in this paper. Intuitively, rheolytic would be more effective than aspiration thrombectomy given the large thrombus loads. The recent JetStent trial suggested that rheolytic thrombectomy was safe in native-vessel STEMI with large thrombus burdens and thrombolysis in myocardial infarction (TIMI) 0 or 1 flow.12 In the setting of a large throm- bus burden and STEMI, rheolytic thrombectomy prior to drug- eluting stents substantially reduced subsequent stent thrombosis.13 A combination of proximal protection along with thrombectomy is a particularly attractive strategy; however, an adequate proximal landing zone is necessary. Early studies in native-vessel STEMI patients have demonstrated, the success of proximal embolic protection.14 Often in the setting of a very large thrombus burden, distal embolic devices, particularly filters, can be overwhelmed. Whether the use of drug-eluting stents is best in occluded grafts is unstudied. In summary, Abdel-karim and colleagues have reinforced the procedural challenges and poor long-term outcomes of those with acutely occluded SVGs. Given these sobering results, the optimal strategy may be as Dr. Sheldon Goldberg suggested: “the best approach to vein grafts is to leave them in the leg.”15
The author reports no conflicts of interest regarding the content herein.
Address for correspondence: James B. Hermiller, MD, FACC, FSCAI, 10590 North Meridian, Indianapolis, IN 4 6290. E-mail: [email protected]
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