Current Trends In Bilateral Internal Mammary Artery Use For Coronary Revascularization : Extending Benefit To High-Risk Patients
Nishant Saran, *David Joyce, Lyle Joyce, John Stulak, Simon Maltais, *Sameh Said, Kevin Greason, Chaim Locker, Alberto Pochettino, Richard Daly, Joseph Dearani, Hartzell Schaff
Mayo clinic, Rochester, MN
Background: Bilateral internal mammary artery (BIMA) use is shown to have a survival advantage over left internal mammary artery and saphenous vein grafts (LIMA-SV) for multivessel coronary artery disease. It is uncertain whether BIMA is beneficial in perceived "high risk" patients. We sought to identify the trends in BIMA use, and impact of patient co-morbidities on relative benefit of BIMA versus LIMA-SV. Methods: A retrospective review of all isolated Coronary artery bypass grafting (CABG) for multivessel coronary artery disease at our institution from 2000 to 2015 was performed. Propensity score matching was done between the BIMA and the LIMA-SV group (1128 matched pairs) to control for age, gender, smoking status, diabetes, body mass index (BMI), peripheral vascular disease, cerebrovascular disease, chronic lung disease (CLD), renal failure, ejection fraction (EF), left main>50%, number of diseased coronary vessels, and emergent surgery. BIMA use in "High risk" patients (EF<30, BMI >30, age>70, diabetes mellitus, CLD, cerebrovascular accident) was evaluated and its effect on survival was sought. We also compared operative, cardiopulmonary bypass (CPB), and cross clamp times between the groups given the potential for these variables to influence conduit selection. Results: A total of 9,084 CABG procedures were performed (7,901 LIMA-SV, 1,183 BIMA) during the study period. There was an increasing trend in BIMA utilization across the 15 year period (P=0.049), with a higher percentage noted in each of the last 5 years, increasing from 11% in 2011 to 25% in 2015. Propensity-matched comparisons showed a survival advantage for the BIMA group (Hazard Ratio 0.80, Confidence Interval 95%, 0.65, 0.98, P =0.028) (Figure 1) but with twice the incidence of sternal site infection (BIMA 3.0%, LIMA 1.4%, P=0.010). None of the "high risk" patient factors had an adverse bearing on the survival of BIMA patients [age >70years (P=0.768), EF <30%(P=0.474), BMI>30 (P=0.250), gender (P=0.642), diabetes mellitus (P=0.699), cerebrovascular accident (P=0.887), CLD (P=0.883), non-elective surgery (P=0.849)] or showed a differential effect of BIMA on sternal site infection. BIMA use was associated with shorter aortic cross clamp time (P<0.001) but higher CPB and incision times (P<0.001). Conclusions: We observed an increased use of BIMA in recent years. Selected "high risk" patients even with age more than 70 years, diabetes mellitus, higher BMI and CLD, can benefit from BIMA over LIMA-SV in multivessel CABG.
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