Contemporary Management of Vein Graft Disease

Despite the promise of new transcatheter technologies, 400,000 coronary artery bypass (CABG) surgeries are performed each year in the United States, the vast majority incorporating saphenous vein grafts (SVG) as conduits.¹ Soon after implantation and exposure to systemic pressure, SVGs undergo intense intimal hyperplasia, followed by accelerated and progressive atherosclerosis.² In comparison to native vessel disease, SVG plaques have a poorly-defined cap, are bulkier, more diffuse and more friable, and have larger amounts of overlying thrombus. During the first year after bypass surgery, 10–15% of vein grafts fail, by 10 years 40–50% are closed, and of those that remain patent, half have significant obstructive disease.^3,4 Options for the patient with vein graft disease include re-operation, percutaneous coronary intervention (PCI) of the native artery, and finally, intervention of the SVG itself. Re-do bypass surgery carries a 3- to 5-fold higher risk of mortality and is often reserved for those not having a LIMA graft and diffuse SVG disease. Unfortunately, many of these patients do not have adequate distal targets or acceptable left ventricular (LV) function for re-do surgery. Particularly in the era of drug-eluting stents (DES), the best option is often stenting of the native coronary artery; regrettably, due to chronic occlusions and/or diffuse disease, this approach is seldom available. Most frequently, the only acceptable strategy is treatment of the vein graft. Accounting for 10–15% of PCIs in most centers, SVG intervention is complicated by high procedural, inhospital, and long-term event rates.^5–7 These patients have a greater atherosclerotic burden, poorer LV function, and a larger number of comorbidities compared to the native-vessel patient. Vein graft PCI has been plagued by three problems: 1) distal embolization, 2) progressive graft disease outside the target lesion, and 3) restenosis. Until the advent of embolic protection devices, SVG intervention suffered from high rates of no-reflow (8% of procedures) and postprocedural myocardial infarction (MI) (17–20% of procedures) secondary to atheroembolic debris.⁸ Occlusive and filter embolic protection have become the standard of care in the management of these patients, reducing MACE rates by 40–50%; however, in approximately one-third of these patients, distal protection cannot be applied due to device constraints.9,10 Covered stents and glycoprotein (GP) IIb/IIIa inhibitors have not been helpful.^11,12 The issue of progressive vein graft disease is an unsolved challenge. In many studies, the higher target vessel revascularization (TVR) in saphenous vein graft intervention was not due to higher restenosis rates at the target, but a 3- to 4-fold higher revascularization rate in the non-target areas.¹³ Moderate disease outside the target is a potent predictor of repeat revascularization as well.¹⁴ Finally, restenosis rates are high, with target lesion revascularization occurring in 20–60% of patients.^15–17 Although randomized studies have demonstrated that bare metal stents improve procedural success compared to balloon angioplasty, their impact on restenosis has been suboptimal. Despite the unambiguous efficacy of DES in native vessels, their role in vein grafts is less certain. In this issue of the Journal, Costa and collegues report the impact of the sirolimus-eluting stent (SES) in no-option bypass patients enrolled in the SECURE registry.¹⁸ In this study of 252 patients, 76 underwent bypass graft intervention, the majority of which were vein grafts. Of the 94 lesions treated, 90.4% had undergone previous intervention, and 67.1% had previous brachytherapy. Acute and 6-month outcomes were surprisingly good. There was one inhospital sudden death (presumably due to stent thrombosis), while all other patients were discharged without complications. TVR at 6 months was 16.7%, which did not differ from the 18.1% of patients in the native-vessel control group. The 12-month MACE rates were more sobering, although not different from the native-vessel group. Other recent reports of DES in de novo vein graft intervention have been encouraging. Hoye et al. reported the results of SES implantation in 19 consecutive patients undergoing de novo SVG intervention. At 1-year follow-up, target lesion revascularization (TLR) was 5%.¹⁹ Ge et al. recently described the results in 61 consecutive patients with de novo SVG lesions treated with DES (both paclitaxel- and sirolimus-eluting stents) and compared those outcomes to 89 patients receiving bare metal stents (BMS) in the preceding 24 months. Cumulative MACE rates at 6 months were 11.5% in the DES group and 28.1% in the BMS group (p = 0.02). TLR was significantly lower in the DES group: 3.3% versus 19.8%. Six-month angiographic follow-up revealed a substantially lower late loss in the DES group (0.37 ± 0.97 versus 1.09 ± 1.10 mm; p = 0.003).20 In another recently published study, Price and colleagues reported the clinical outcomes of 35 patients who underwent SES implantation for bypass graft disease. At a mean follow-up of 7.5 months, there was 1 cardiac death, presumably due to stent thombosis, and TVR occurred in 2 patients (6%). Most MACE events were related to disease in nontarget vessels.²¹ How are interventionalists to use these data? Certainly the patients described in the SECURE registry are at the highest risk for restenosis, most having had multiple procedures for in-stent restenosis, including brachytherapy. This study, however, is consistent with other reports that the favorable impact of DES on restenosis in vein grafts is similar to that observed in native vessels, including a substantial reduction in late loss. Although it would be ideal to have a randomized trial comparing DES to BMS in vein grafts, it is increasingly less feasible due to ethical issues in treating this high-risk subgroup with bare metal stents; however, well-designed, larger registries with longer-term follow-up periods are needed.²⁰ Also, stents designed specifically for the vein graft application (larger stents with high radial strength) are necessary. Until further data are available, the use of DES in appropriately-sized vein grafts appears to be a favorable approach. In combination with embolic protection, DES have transformed vein graft intervention from an often untreatable problem to a manageable challenge. Email: jhermill@TheCareGroup.com

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