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Ann Thorac Surg 2006;82:805
© 2006 The Society of Thoracic Surgeons
Cardiovascular Surgery, Sunnybrook & Women's Health Science Center, 2075 Bayview Ave, Room H405, Toronto, Ontario M4N 3M5, Canada
(Email: bernard.goldman{at}sunnybrook.ca).
Gaudino and colleagues [1] have made an interesting and provocative observation that saphenous vein grafts (SVGs) fare poorly in patients undergoing coronary bypass grafting (CABG) after failed intracoronary stents. They hypothesize that patients with in-stent stenosis have an aggressive atherosclerotic disorder that prejudices the fate of both the stent and a subsequent vulnerable vein bypass compared with the internal mammary artery (IMA) or other arterial conduit.
Given the tremendous increase in the deployment of intracoronary stents as primary therapy, it is likely that there will be a consequent need for later surgical revascularization despite optimistic claims of markedly reduced restenosis rates. In-stent stenosis is presumed to be mainly due to a local reaction to injury, with fibromuscular hyperplasia, delayed inflammatory reaction, local hypersensitivity, or local factors that affect the actual implant (eg, severe calcification, improper deployment, etc). The report does not mention the type of lesion, diameter of the vessel, state of the distal vessel, length of stent, or the use of antiplatelet agents.
The authors are to be congratulated for their meticulous follow-up with 100% angiographic control at 5 years after operation. Although a retrospective study, data was collected prospectively as part of an ongoing evaluation of arterial and venous bypass grafts. The implication of the study is that only arterial grafts should be used in the revascularization of patients with in-stent stenosis.
The study has certain limitations, particularly with the small number of patients in each group: 60 patients with previous in-stent stenosis received 84 vein grafts to the circumflex or right coronary arteries and are compared with 60 control patients who received 81 vein grafts to the same systems. Perfect patency was achieved in only 33% of the restenosis group (SVGs) compared with 61.7% in the control groups. The IMA graft patency in these two groups was similar and unaffected by the presence of previous in-stent stenosis. Of the 60 patients studied in the restenosis group, only 45 vein grafts were placed distal to a failed stent (ie, in the same vessel). Restenosis rates in the circumflex and right coronary arteries are generally lower than in the left anterior descending coronary artery, which does suggest some other process or local problem.
The 15 SVGs placed in vessels other than those with in-stent stenosis were presumably for new stenotic lesions or progression of previously mild lesions. This could substantiate the hypothesis of an aggressive and progressive systemic atherosclerosis, but presumably, other indicators of inflammation or lipid disorder might have been predictors of late failure, such as levels of low-density lipoprotein and C-reactive protein.
The authors do acknowledge a significant incidence of diabetes in the restenosis group (40 patients) versus the control (22 patients). Diabetes is well known to be associated with a high atherosclerotic burden and a higher incidence of stent failure as well as progressive vein graft attrition. Diabetes is associated with a downregulation of thrombin receptors and reduced production of nitric oxide in both stented lesions and vein grafts. Diabetes is also associated with other aspects of an aggressive atherosclerotic process such as hypertension, vasoconstriction, platelet aggregation, and decreased fibrinolytic activity.
It is likely that many patients will ultimately come to subsequent CABG surgery for progressive disease or stent failure after initial percutaneous coronary interventions. The problem I encounter is that the failed stent is not always 90% stenotic or 100% occluded, and thus, a SVG is often the conduit of choice because of the possible failure of radial artery grafts in patients with less than 70% to 90% proximal vessel stenosis. Because there is a limit to how many native vessels can be bypassed with bilateral IMA grafts and although the radial artery has become the most important complimentary conduit, SVGs do get used very commonly and especially if the distal vessel requires endarterectomy.
Nonetheless, I do appreciate the message inherent in this study and will be more aggressive about antiplatelet agents, including clopidogrel and high-dose statin therapy, in patients who do receive a vein graft to the right or circumflex vessels after previous in-stent stenosis. As cardiac surgeons encounter more patients from the mid-1990s with in-stent problems and especially those with repeated percutaneous coronary interventions, the need to consider arterial versus venous conduit will become even more important to provide such patients with better long-term graft function and improved prognosis.
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  J. Chikwe, T. Athanasiou, P. Collins, and J. R. Pepper Safety and efficacy concerns regarding elective coronary artery surgery in patients with prior coronary stents Eur. Heart J., May 2, 2007; 28(10): 1265 - 1265. [Full Text] [PDF]
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