Computed Tomography to Predict Surgical Revascularization of a Left Anterior Descending Artery Occlusion Incompletely Visualized by Conventional Angiography

Abstract

Previous studies demonstrated that failure to visualize distal chronic total occlusion in conventional coronary angiography (CCA) does not preclude procedural success of coronary artery bypass grafting (CABG). We assessed the utility of computed tomography angiography (CTA) in guiding CABG to the occluded left anterior descending artery (LAD) incompletely visualized by CCA. Twenty-four symptomatic patients rejected for revascularization of an occluded LAD on the basis of CCA underwent a preoperative CTA before intended transmyocardial laser revascularization. Off-pump CABG to the LAD was attempted in all patients depending on the intraoperative findings. The primary outcome was defined as procedural success of CABG to the LAD. The success rate for CABG was 79.2%. By CCA, Rentrop 0/1 was present in 6 patients (25%), whereas Rentrop 2 was present in 18 patients (75%). By CTA, Rentrop 3 was seen in all patients. Compared with the CABG-failure group, the CABG-success group showed a larger mean distal LAD diameter (1.7 ± 0.2 mm vs. 1.3 ± 0.1 mm; P=0.001). By receiver-operating curve analysis, a cutoff value of 1.5 mm for the mean distal LAD diameter predicted CABG availability with 100% specificity and 95% sensitivity. The distal LAD short length and intramyocardial course were other significant correlates of CABG failure compared with CABG success (60% vs. 5.3%, P=0.018; 80% vs. 0%, P<0.001). Noninvasive CTA is not only superior to CCA in delineating distal coronary occlusion but also very precisely predicts the procedural success of CABG. CTA represents a robust evaluation tool for coronary mapping of chronic total occlusion with doubtful distal anatomy in CCA.