Occurrence rate and fate of competitive flow of the left internal thoracic artery used in Y-composite grafts.

Objectives: We evaluated the occurrence rate of competitive flow and the fate of grafts of left internal thoracic artery (LITA)-to-left anterior descending coronary artery (LAD) anastomosis after coronary artery bypass grafting with Y-composite grafts using early and 1-year angiography. Methods: From 2008 to 2017, 923 patients underwent off-pump coronary artery bypass grafting using Y-composite grafting based on the in situ LITA. Early postoperative angiography was performed for all patients. One-year angiography (mean, 13.2 ± 3.1 months) was performed for 86.7% (800 of 923) of patients. Results: The early occlusion rate of LITA with Y-composite graft (CompLITA) to LAD was 0.7%. Among 917 patent CompLITA-LAD grafts, competitive flow was observed in 39 patients (4.3%). Multivariable analysis showed that the degree of LAD stenosis (odds ratio, 0.897; 95% CI, 0.875-0.920; P < .001) and 3-vessel disease (odds ratio, 5.632; 95% CI, 1.168-27.155; P = .031) were factors associated with the occurrence of competitive flow of CompLITA-LAD grafts. The receiver operating characteristics curve determined that the cutoff degree of LAD stenosis was 82.5% (sensitivity 82.1% and specificity 85.2%). The failure rate of CompLITA-LAD grafts seen on 1-year angiography was 58.3% in patients with competitive flow. Among patients with competitive flow, left main coronary artery disease was a protective factor (odds ratio, 0.055; 95% CI, 0.009-0.337; P = .002) against graft failure of the CompLITA-LAD seen on 1-year angiography. Conclusions: In CompLITA-LAD, the degree of LAD stenosis and combined 3-vessel disease were associated with the occurrence of competitive flow. CompLITA-LAD grafts with early competitive flow showed a high 1-year graft failure rate of 58%.