Chronic Total Occlusion in Patients After Coronary Artery Bypass Grafting: A Review of Possible Interventions and Results With a Case Study

Abstract

Within 10 years following a coronary artery bypass graft (CABG), only 60% of vein grafts and 90% of internal mammary artery (IMA) grafts remain patent. Chronic total occlusion (CTO) in patients after a CABG exhibits more advanced stable atherosclerosis. Although the precise mechanism of atherosclerosis in these patients is unknown, several clinical studies have reported that atherosclerotic progression occurs more rapidly in grafted arteries than in non-grafted arteries. These data support the fact that the IMA has a favourable metabolic effect not only in the bypass, but also in the bypassed artery, which is defined by nitric oxide products. The occlusion frequency of the initial stenotic artery in the proximal or distal segment was ~22% after application of the IMA, and on average 48% after an autovenous bypass. In multivariate analyses, bypass interventions are independently associated with higher hospital mortality and peri-operative complications. Mortality was 2.6% if artery recanalisation was successful, 5.2% in the case of partial success, and 8.2% in the case of failure. However, due to the difficulty of access, spastic reactions, the small diameter of the artery, and a large area of myocardium that feeds the IMA, use of the IMA for CTO recanalisation is limited. A case study of CTO intervention is used to describe the retrograde approach to CTO of the left anterior descending coronary artery through the IMA and diagonal branch in a patient after a CABG 10 years ago. Two microcatheters were used, and the operation was successfully completed in two stages because of unstable patient condition.