Does previous percutaneous coronary intervention increase the risk of graft failure in subsequent coronary surgery?

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CTSNet classification: 23

To the Editor:

We recently pointed out¹ that there is no evidence to support significantly better angiographic patency with radial artery conduit than with saphenous vein graft in coronary artery bypass grafting in controlled, randomized trials reported to date. We do not, however, support inclusion of data extracted from the article by Gaudino and associates² in the recently published meta-analysis by Benedetto and colleagues³ of controlled, randomized trials comparing radial artery conduits and saphenous vein grafts with respect to angiographic patency.

The article by Gaudino and associates² reported 2 controlled, randomized trials including patients with previous percutaneous stent implantation (in any coronary vessel) with preoperative angiographic confirmation of a failed (I trial) or patent (II trial) intracoronary stent. In that report,² they focused on the results of arterial versus venous grafts directed to the first obtuse marginal artery. There were, however, no data on failed stent location. In a subsequent analysis⁴ of that initial report, Gaudino and coworkers⁴ focused on the complementary venous grafts to nonobtuse target coronary vessels (right coronary artery and circumflex artery other than the first obtuse marginal artery). They concluded that patients with development of in-stent restenosis face a higher risk of early venous graft failure (46 occluded of 84, patency rate 45.2% at 5 years after surgery). Even in that article, however, there were no precise data about the number of failed venous grafts that were distributed to targeted coronary arteries with in-stent restenosis. We were able to find out only that 25 of the failed stents were located on a circumflex artery other than the first obtuse marginal artery, 31 were located on the right coronary artery, and 7 were located on the left anterior descending coronary artery. Although 43 venous graft–targeted vessels were circumflex artery other than the first obtuse marginal artery and 41 were right coronary artery, we must face the possibility that the vast majority of venous grafts were placed on previously stented coronary arteries.

It has been argued by Gaudino and associates², ⁴ that in-stent restenosis is seen in a subgroup of patients with aggressive coronary atherosclerosis. Conversely, the pathophysiologic response⁵ to the presence of an intravascular foreign body (stent) may also adversely affect the fate of the conduits used to graft stented coronary arteries. Stenting can cause prolonged endothelial dysfunction, as well as an acute and chronic inflammatory reaction, even during the late period, with involvement of the distal coronary artery and surrounding myocardium.⁵ This may adversely affect anastomosis sites in patients who subsequently undergo coronary artery bypass grafting.

A vexed question is whether the poor fate of venous conduits used to bypass coronary arteries with in-stent restenosis is due to aggressive atherosclerosis or to an inflammatory reaction involving downstream coronary artery beds. Although we do not know the distribution of occluded conduits with respect to stent locations, we cannot definitively point out the influences on graft patency. We therefore do not support inclusion of these data in meta-analyses.

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References 

1. Nezic D, Knezevic A, Cirkovic M. Are we allowed to declare radial artery graft with a ‘string sign’ for a patent conduit?. Eur J Cardiothorac Surg. 2009;36:605–606
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2. Gaudino M, Cellini C, Pragliola C, Trani C, Burzotta F, Schiavoni G, et al. Arterial versus venous bypass grafts in patients with in-stent restenosis. Circulation. 2005;112(9 Suppl):I265–I269
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3. Benedetto U, Angeloni E, Refice S, Sinatra R. Radial artery versus saphenous vein graft patency: meta-analysis of randomized controlled trials. J Thorac Cardiovasc Surg. 2010;139:229–231
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4. Gaudino M, Luciani N, Glieca F, Cellini C, Pragliola C, Trani C, et al. Patients with in-stent restenosis have an increased risk of mid-term venous graft failure. Ann Thorac Surg. 2006;82:802–805
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5. Gomes W, Buffolo E. Coronary stenting and inflammation: implications for further surgical and medical treatment. Ann Thorac Surg. 2006;81:1918–1925
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