Effect of the Left Internal Mammary Artery to the Left Anterior Descending Artery on Mortality and Morbidity After Combined Coronary and Valve Operations

Background The effect of using the left internal mammary artery in combined coronary and valve operations have not been fully investigated. We aimed to quantify the impact of the left internal mammary artery to the left anterior descending artery on early and mid-term outcomes in these patients. Methods Data was collected prospectively on 630 consecutive patients who underwent revascularization of the left anterior descending artery with concomitant valve operations between April 1997 and March 2003. Multivariate logistic regression and Cox proportional hazards analyses were used to adjust in-hospital outcomes and Kaplan-Meier survival curves. A propensity score for left internal mammary artery use was constructed to control for selection bias. Results The left internal mammary artery was used in 478 (75.9%) patients. Univariate analyses found left internal mammary artery patients had significantly lower in-hospital mortality (6.3% versus 13.2%; p< 0.01) and postoperative renal failure (8.2% versus 13.8%; p = 0.038). After adjusting for treatment selection bias, in-hospital mortality (adjusted odds ratio, 0.77; p = 0.45) and renal failure (adjusted odds ratio, 0.94; p = 0.86) were no longer significantly different. A total of 171 (27.1%) deaths occurred during the follow-up, with a total follow-up of 2,325 patient-years. The crude relative risk for the left internal mammary artery was 0.67 (p = 0.015). After adjusting for the propensity score, the adjusted relative risk was 0.91 (p = 0.62). Conclusions The left internal mammary artery does not adversely affect the short-term and medium-term outcomes in patients undergoing concomitant coronary and valve operations. Survival at 7 years was similar with or without the use of the left internal mammary artery.