Free LIMA Graft with Proximal Aortic Anastomosis for Intraoperative Proximal LIMA Injury: Short- and Mid-Term Outcomes of a Conduit-Preserving Salvage Strategy

Abstract

Background: The left internal mammary artery (LIMA) is the gold-standard conduit for left anterior descending (LAD) coronary revascularization. Proximal LIMA injury during harvest is a rare but technically challenging complication that may result in loss of the optimal arterial conduit. We evaluated the feasibility, safety, and short- to mid-term outcomes of a conduit-preserving salvage strategy using free LIMA grafting with proximal anastomosis to the ascending aorta. Methods: A retrospective analysis of a prospectively maintained multicenter registry was conducted across four high-volume cardiac centers between January 2018 and December 2021. Patients undergoing coronary artery bypass grafting (CABG) complicated by intraoperative proximal LIMA injury (≥50% transection, critical stenosis, or pedicle avulsion) were included. Salvage was performed by converting the LIMA into a free graft, with proximal anastomosis to the ascending aorta and distal anastomosis to the LAD. Intraoperative graft flow was assessed using transit-time flowmetry (TTFM). Primary endpoints were 30-day major adverse cardiac and cerebrovascular events (MACCE: all-cause mortality, myocardial infarction, stroke, or repeat revascularization) and graft patency at follow-up. Graft patency was assessed using MSCT coronary angiography at 12 months or during follow-up when feasible and graded according to the Fitzgibbon classification (A: excellent; B: <50% stenosis; O: occlusion or ≥50% stenosis). Outcomes were compared with a 1:1 propensity-matched cohort (n=52) undergoing standard in-situ LIMA-to-LAD grafting, matched for age, sex, LVEF, diabetes, redo status, and graft number. Kaplan–Meier survival analysis and Cox proportional hazards regression were used for comparative outcomes. Results: Fifty-two patients underwent attempted LIMA salvage. Technical success, defined as satisfactory intraoperative flow by TTFM, was achieved in 50 patients (96.2%). Mean age was 64.2 ± 8.1 years, and 78.8% were male. The 30-day MACCE rate was 9.6% (5/52), including mortality in 3.8% (n=2), non-fatal myocardial infarction in 3.8% (n=2), and stroke in 1.9% (n=1); no repeat revascularization occurred within 30 days. MSCT coronary angiography follow-up was available in 48 of 50 successfully treated patients (96.0%) at a mean follow-up of 26.4 ± 4.2 months (range 18–38); the remaining two patients were excluded due to pre-existing renal dysfunction precluding contrast administration. Overall graft patency (Fitzgibbon grade A or B) was 93.4% (45/48), with perfect patency (grade A) in 89.6% (43/48). Compared with the propensity-matched in-situ LIMA cohort, all-cause mortality did not differ significantly (adjusted hazard ratio 1.07, 95% CI 0.89–1.29; p = 0.51). The study was not powered to demonstrate equivalence between groups. Conclusions: Conversion of an injured LIMA to a free graft with proximal anastomosis to the ascending aorta is a feasible and effective conduit-preserving salvage strategy. It provides favorable short- to mid-term patency and acceptable clinical outcomes compared with standard in-situ LIMA grafting. This technique may be considered in selected intraoperative injury scenarios when anatomically feasible to preserve arterial revascularization options.