Coronary computed tomographic angiography for prediction of procedural and intermediate outcome of bypass grafting to left anterior descending artery occlusion with failed visualization on conventional angiography

Abstract

Conventional coronary angiography (CCA) has considerable limitations regarding visualization of distal vessel segments in chronic total occlusion. We assessed the ability of coronary computed tomographic angiography (CCTA) to predict the success of coronary artery bypass grafting (CABG) to the chronically occluded left anterior descending coronary artery (LAD) incompletely visualized on CCA. Thirty symptomatic patients rejected for CABG on the basis of the CCA findings underwent preoperative CCTA before intended transmyocardial laser revascularization. The LAD was explored operatively in all patients, and CABG to the LAD was attempted if the distal vessel was suitable for anastomosis. The procedural outcome of CABG and the 6-month patency of the left internal mammary artery graft at follow-up CCTA were defined as the primary and secondary end point, respectively. The primary and secondary end points were achieved in 80% and 77% of patients, respectively. We found a significant correlation between the intraoperative and computed tomographic measurement of distal LAD diameter (R = 0.428, p = 0.037). On multivariate analysis, the maximum diameter of the distal LAD by CCTA (odds ratio 8.16, p = 0.043) was the only independent correlate of procedural success of CABG. A cutoff value of 1.5 mm for the mean distal LAD diameter predicted left internal mammary artery graft patency with 100% specificity and 83% sensitivity. Successful CABG resulted in significant improvements in angina class and left ventricular function in LAD segments at 6 months of follow-up. In conclusion, CCTA predicted both the procedural and the intermediate outcome of CABG to chronic LAD occlusion with failed visualization on CCA.