Midterm Follow-up of Coronary Artery Bypass Grafting with 64-Slice Multi-detector Computed Tomography:Identification of Risk Factors Affecting Graft Patency

Objective To identify the risk factors that are associated with the midterm coronary artery bypass grafting (CABG) functionality by assessing patency of left internal mammary artery (LIMA) graft and saphenous vein (SV) graft with 64-slice multi-detector computed tomography (64-MDCT). Methods Patients who underwent CABG operation and postoperative 64-MDCT follow-up examinations from August 2012 to December 2015 were included. The graft patent status was classified into patent and poor patent according to MDCT findings predominantly on 3D reconstructed images by two radiologists. The clinical data and imaging findings of the patients were collected and compared between the patent group and poor patent group. Univariate analysis and the multivariate logistic regression analysis were performed to identify the risk factors that affect graft patency. Results Among 341 patients in the study, there were 330 LIMA grafts 326 anastomosed to the left anterior descending artery (LAD), 4 to right coronary artery (RCA)] and 564 SV grafts (SVG) 100 anastomosed to the diagonal branch (D), 226 to the obtuse marginal branch (OM), and 238 to the RCA territory]. The approximal vessel stenosis exceeding 90% occurred in 268 of 292 patent LIMA grafts, and in 1 of 34 poor patent grafts (χ2=167, P<0.001). The patency rate was higher when SVG was anastomosed to OM (85.4%) or RCA territory (81.9%) than to D (69.0%) ( χ2=15.471, P=0.004). The proximal target vessel stenosis<90% ( OR=0.015, 95% CI: 0.01-0.14, P=0.000) was independently associated with the closure risk of LIMA grafts, the dyslipidemia (OR=1.52, 95% CI: 1.0-2.5, P=0.048), history of diabetes (OR=1.28, 95% CI : 0.90-2.26, P=0.045) and typical angina symptoms (OR=1.81, 95% CI :1.33-4.15, P=0.003) were independently associated with the closure risk of SVG. Conclusions The proximal LAD stenosis less than 90% was adversely associated with graft patency in LIMA recipients; dyslipidemia, diabetes and angina symptoms were associated with the midterm failure in SVG recipients. The choice of the target anastomosis sites may affect the patency of SVG.