The effects of using a radial artery in patients already receiving bilateral internal mammary arteries during coronary bypass grafting: 30-day outcomes and 14-year survival in a propensity-matched cohort

OBJECTIVES: Recent studies have demonstrated the superiority of bilateral internal mammary arteries (BIMAs) as conduit material for coronary artery bypass grafting (CABG) surgery. However, there is limited research on the effects of other graft conduits used in patients who require additional bypasses. The goal of this study was to evaluate the impact of the radial artery (RA) when used in conjunction with the BIMAs. METHODS: From the beginning of 2000 to the end of 2013, 4370 patients underwent CABG for three or more vessels at our institution. There were 568 and 183 patients who received BIMA + saphenous vein graft (SVG) and BIMA + radial +/- SVG, respectively. Propensity matching was used to create a balanced cohort from these patients, which resulted in two groups of 183 patients. Thirty-day outcomes and long-term survival were compared between the two groups. Long-term follow-up was generated using the Social Security Death Index. RESULTS: There were no significant differences in preoperative characteristics. For 30-day outcomes, the BIMA + radial +/- SVG group had more postoperative atrial fibrillation (24.6 vs 12.0%; P = 0.001) and a longer median postoperative length of stay (6 vs 5 days; interquartile range = 2; P = 0.016) than BIMA + SVG patients. There was no significant difference in long-term survival between the two groups over the 14-year period. However, before year 10, the BIMA + SVG group had a trend towards higher survival, whereas on follow-up after 10 years, there was a trend that favoured the BIMA + radial +/- SVG patients. Cox regression analysis using a time-dependent covariate demonstrated that when the groups were split at 10 years, there was a statistically significant improvement in survival of the BIMA + radial +/- SVG group [adjusted hazard ratio 0.254 95% confidence interval (CI) 0.062-0.977; P = 0.048] over BIMA + SVG patients between 10 and 14 years. CONCLUSIONS: Overall, there were no statistically significant differences in survival between the BIMA + SVG and BIMA + radial +/- SVG groups over the 14 years. However, further analysis demonstrated that while the BIMA + radial +/- SVG group had a trend towards decreased survival before 10 years, use of the RA in conjunction with BIMAs was associated with significantly increased survival in the later years. A larger cohort of patients with longer follow-up is needed to assess the outcomes of CABG using BIMA + radial +/- SVG.