Angiographic Fate of Collateral Vessels After Surgical Revascularization of the Totally Occluded Left Anterior Descending Artery

Background: Coronary artery bypass grafting (CABG) is best indicated for chronic total occlusion of the left anterior descending artery (LAD) with collaterals. We investigated angiographic changes in the collateral circulation after CABG. Methods: Preoperative and postoperative angiograms were reviewed in 42 patients who underwent grafting onto occluded LADs. We described the type, location, and size of collaterals, the Rentrop grading, and collateral frame count (CFC). Regional wall motion of the LAD area was also evaluated with the centerline method. Postoperatively, we measured the lengths of LAD proximal (Lp) and distal (Ld) to the graft anastomotic site. Results: Preoperative collaterals comprised 78 pathways (septal 42%, branch-branch 20%, atrial 19%, bridging 18%). After CABG, residual collaterals were identified, mainly through the septal pathways, in 6 patients (14%), most of whom were diabetic. The residual collaterals were a part of those which had been opacified in earlier phases of the preoperative angiograms (CFC: 17 ± 3 vs 25 ± 15, p = 0.01). Also, the Ld was shorter in these patients so that Lp/Ld was greater than in patients without residual collaterals (0.80 ± 0.24 vs 0.53 ± 0.28, p = 0.04). We found no association of residual collaterals with the improvement of LAD regional wall motion after CABG. Conclusions: Even after successful CABG, some collaterals with earlier filling of the LAD remain, mainly through the septum. Although the clinical significance remains to be clarified, complex and diffuse atherosclerosis associated with more distal graft anastomoses may contribute to maintaining collaterals after CABG to the occluded LAD, especially in diabetic patients.