Long-term outcome of the in-situ versus free internal mammary artery as the second arterial graft

Abstract: Objectives To determine the impact on outcome associated with using the second internal mammary artery (IMA) as a free compared to an in-situ graft among patients who received the first IMA as an in-situ IMA to the left anterior descending artery (LAD). Methods Among 2,600 patients that underwent bilateral IMA (BIMA) with an in-situ IMA to the LAD, the second IMA was used as a free graft (f-BIMA) in 136, and as an in-situ graft (is-BIMA) in 2,464 patients. One-to-many propensity-score matching was performed to produce a cohort of 134 patients with a second f-IMA matched to 2,359 patients with a second is-IMA. Early and long-term outcomes including survival, hospital readmission, and repeat revascularization up to a maximum of 25.8 years were compared. Results There were no differences between the two matched groups’ preoperative baseline characteristics and early adverse events. Long-term survival at 5, 10, and 15 years was significantly higher among is-BIMA patients compared to f-BIMA patients (hazard ratio (HR) f-BIMA vs. is-BIMA=1.53, 95% CI 1.14–2.10, p=0.004). However, the long-term risk of readmission to hospital for cardiovascular reasons and repeat revascularization were not significantly different between the two matched groups. Conclusions In a small, propensity matched cohort of patients undergoing CABG, the use of a second in-situ IMA was associated with an increase in late survival compared to the use of a second IMA as a free graft. However, the risk of late hospital readmission and the need for repeat revascularization were similar.