Patency of conduits in patients who received internal mammary artery, radial artery and saphenous vein grafts

Alistair Royse,Colin Royse,William Pamment,Andrew Ajani,William Wilson,David Eccleston,Sandy Clarke-Errey,David Canty,Zulfayandi Pawanis

doi:10.1186/s12872-020-01433-0

Abstract

BackgroundWhere each patient has all three conduits of internal mammary artery (IMA), saphenous vein graft (SVG) and radial artery (RA), most confounders affecting comparison between conduits can be mitigated. Additionally, since SVG progressively fails over time, restricting patient angiography to the late period only can mitigate against early SVG patency that may have occluded in the late period.MethodsResearch protocol driven conventional angiography was performed for patients with at least one of each conduit of IMA, RA and SVG and a minimum of 7 years postoperative. The primary analysis was perfect patency and secondary analysis was overall patency including angiographic evidence of conduit lumen irregularity from conduit atheroma. Multivariable generalized linear mixed model (GLMM) was used. Patency excluded occluded or “string sign” conduits. Perfect patency was present in patent grafts if there was no lumen irregularity.ResultsFifty patients underwent coronary angiography at overall duration postoperative 13.1 ± 2.9, and age 74.3 ± 7.0 years. Of 196 anastomoses, IMA 62, RA 77 and SVG 57. Most IMA were to the left anterior descending territory and most RA and SVG were to the circumflex and right coronary territories. Perfect patency RA 92.2% was not different to IMA 96.8%, P = 0.309; and both were significantly better than SVG 17.5%, P < 0.001. Patency RA 93.5% was also not different to IMA 96.8%, P = 0.169, and both arterial conduits were significantly higher than SVG 82.5%, P = 0.029. Grafting according to coronary territory was not significant for perfect patency, P = 0.997 and patency P = 0.289. Coronary stenosis predicted perfect patency for RA only, P = 0.030 and for patency, RA, P = 0.007, and SVG, P = 0.032.When both arterial conduits were combined, perfect patency, P < 0.001, and patency, P = 0.017, were superior to SVG.ConclusionsAll but one patent internal mammary artery or radial artery grafts had perfect patency and had superior perfect patency and overall patency compared to saphenous vein grafts.

Highlights

Where each patient has all three conduits of internal mammary artery (IMA), saphenous vein graft (SVG) and radial artery (RA), most confounders affecting comparison between conduits can be mitigated
This is different to SVG which rarely appears normal in the late period, with most (82.5% in this series) having some lumen irregularity consistent with conduit wall atheroma
The conclusion to be drawn is that a diseased conduit such as SVG may be expected to have ongoing progressive atheroma formation which may cause graft failure by way of hemodynamically significant stenosis or occlusion; whereas the normal arterial conduits may be expected to remain normal indefinitely

Summary

Introduction

Where each patient has all three conduits of internal mammary artery (IMA), saphenous vein graft (SVG) and radial artery (RA), most confounders affecting comparison between conduits can be mitigated. Our institutional practice had relatively few patients that received all three conduits of internal mammary artery (IMA), radial artery (RA) and saphenous vein (SVG) at the same time, with subsequent experience being predominantly total arterial revascularization [1, 2]. Arterial conduits may fail in the early period thought to relate to flow competition from the native coronary circulation but with little evidence of progressive failure over the mid or late postoperative periods. We previously found that there was reduced survival even with the use of a single SVG as well as for multiple SVG conduits when compared to total arterial revascularization [11]

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Results

Conclusion