Single IMA {Single Arterial} Bi-Lateral Internal Mammary Artery (BIMA) Grafting Confers Improved Long-Term Survival After CABG Surgery Compared to Single IMA Grafting Ryan P Kelly, Karen J Buth, Jean-Francois Légaré Dalhousie University, Faculty of Medicine, Division of Cardiac Surgery, Halifax, Nova Scotia, Canada Grafting Strategy Long-Term Results BACKGROUND: The primary objective of this study was to examine the effect of different arterial grafting strategies in CABG surgery on long-term mortality. METHODS: All consecutive CABG surgeries excluding redo operations performed at a single tertiary care center between 1995-2007 were reviewed. Long-term survival rates were compared among patients based on the use of no arterial graft (all saphenous vein), single arterial graft, and multiple arterial grafts. Groups were also stratified based on the type of arterial grafts used (bilateral internal mammary arteries (BIMA) vs. multiple arterial grafts with only one IMA). Cox proportional Hazards ratio models were generated to adjust for differences in clinical presentation between the CABG groups. RESULTS: A total of 8570 isolated CABG operations were preformed at our institution during that period. These patients were followed for a median time of 3.5 years (IQR=1.1-6.4). In this patient population, a single arterial graft was performed in the majority of patients (63%; n=5637) with 28% of patients (n=2532) receiving multiple arterial grafts. Patients who received multiple arterial grafts were more likely to be young, male, and undergo non-urgent surgery. After adjusting for these differences, patients who received any arterial graft were shown to have improved survival when compared to patients who did not (HR=0.75; CI=0.65-0.85). However when single arterial grafts were compared to multiple arterial grafts no incremental survival benefit was apparent except for BIMA use. Among patients who received multiple arterial grafts, percent survival for patients with BIMA grafts at 10 years was 71.6% compared to 66.6% for multiple arterial without BIMA and 66.5% for patients with single arterial grafts (p<0.0001). CONCLUSIONS: We were able to show that after adjusting for differences in clinical presentation multiple arterial grafting, specifically with BIMA grafting, is a strong independent predictor of long-term survival among CABG patients. This observation emphasizes the benefit of BIMA grafting, and suggests that in suitable candidates BIMA grafting should be considered the ideal revascularization strategy. Impact of BIMA Grafting on Survival Adjusted for Clinical Characteristics Impact of BIMA Grafting on Readmission Adjusted for Clinical Characteristics 8570 Isolated CABG 1995-2007 5437 Single Arterial Graft 2448 Multiple Arterial Grafts 685 SVG Only 1079 BIMA Grafts 1369 IMA + Other Background CABG surgery is the established treatment for LM and multi- vessel CAD with excellent short and intermediate-term outcomes Long-term results affected by vein-graft failure: Intimal hyperplasia Graft atherosclerosis Strong evidence supports LIMA to LAD due to: Superior graft patency Fewer cardiac events Enhanced survival compared to SVG alone Is there survival advantage for bilateral internal mammary artery (BIMA) over Single IMA? ] BIMA BIMA * Single IMA Single IMA ] ] * * SVG Only SVG Only SVG Only Single IMA BIMA 5 Year 82% (± 3%) 86% (± 2%) 88% (± 2%) 10 Year 59% (± 5%) 66% (± 4%) 71% (± 4%) SVG Only Single IMA BIMA 5 Year 77% (± 4%) 83% (± 3%) 85% (± 3%) 10 Year 59% (± 6%) 68% (± 5%) 72% (± 5%) 6806 Single IMA Number of patients at risk 1079 976 845 575 414 231 BIMA 6806 5661 4501 3172 1954 979 Single IMA 685 494 374 251 177 106 SVG Only Number of patients at risk 1061 904 737 473 317 171 BIMA 6664 5176 3863 2547 1468 671 Single IMA 638 428 299 172 116 66 SVG Only Univariate Analysis Arterial Grafting Adjusted Hazard Ratio 95% CI p - value BIMA 0.81 (0.68-0.98) 0.0260 SVG Only 1.34 (1.17-1.53) 0.0001 Arterial Grafting Adjusted Hazard Ratio 95% CI p - value BIMA 0.86 (0.73-1.01) 0.0580 SVG Only 1.39 (1.17-1.64) 0.0002 Grafting Strategy Methods All consecutive CABG surgeries excluding redo surgery performed at a single tertiary care center between 1995-2007 were reviewed Univariate analysis of clinical characterstics by grafting strategy Rate of long-term survival and readmission for cardiac cause were compared based on grafting strategy Cox proportional hazards models were generated to adjust for differences in clinical characteristics between groups Clinical Characteristics SVG Only n = 685 (%) Single IMA {Single Arterial} n = 5437 (%) Single IMA {IMA + other} n = 1369 (%) BIMA n = 1079 (%) p - value Mean Age (SD) 70.2 (10.4) 65.5 (10.1) 62.0 (10.1) 58.5 (10.0) <0.0001 Incomp Revasc 26.4 19.7 17.9 12.0 Female 34.9 26.6 18.6 18.0 BMI > 35 9.6 11.4 11.3 9.1 Diabetes 34.5 36.9 37.0 25.6 Renal Failure 12.3 5.5 3.0 1.8 PVD 25.0 16.8 14.3 CVD 16.6 13.9 10.2 9.4 COPD 23.2 14.2 12.9 10.7 EF < 40% 23.1 12.7 8.0 7.2 CHF 25.4 14.5 9.3 6.4 Urgent Status 36.2 16.1 10.0 9.7 LAD Disease 76.8 94.8 93.1 94.0 LAD Graft 71.8 98.1 96.1 96.5 Conclusions Compared to the use of a single IMA or vein grafting alone, BIMA grafting independently predicts a long-term survival advantage and a significant reduction in the rate of readmission to hospital for cardiac cause including ACS, PCI, or CABG In suitable candidates, BIMA grafting should be considered the ideal revascularization strategy