Is the right internal thoracic artery superior to saphenous vein for grafting the right coronary artery? A propensity score based analysis

Objectives While the use of the right internal thoracic artery (RITA) as second arterial conduit to graft the left coronary system has been consistently shown to provide a survival benefit when compared to saphenous vein graft (SVG), the choice of conduit for the right coronary artery (RCA) system remains controversial. We compared long term (>15 years) survival in patients who underwent RITA-RCA versus SVG-RCA grafting at a single institution. Methods The study population consisted of 7223 patients undergoing coronary artery bypass graft surgery. Of them 245 (3.4%) and 6978 (96.6%) received RITA-RCA and SVG-RCA graft respectively. Propensity score (PS) matching and time-segmented Cox regression were used to compare the two groups. Results Survival probability at 5,10 and 15 years were 95.9%[93.4-98.4] versus 96.0%[94.3-97.8], 89.8%[85.9-93.7] versus 88.0%[85.0-91.0] and 82.9%[77.6-88.2] versus 76.3[72.0-80.5] in the RITA-RCA and SVG-RCA group respectively (Figure 2). Time segmented Cox regression showed that during the first 9 years, the two strategy were associated with comparable risk of death (HR 1.13;95%CI 0.67-1.90; P=0.65) but beyond 9 years, the RITA-RCA was associated with a significantly lower risk of death (HR 0.43;95%CI 0.22-0.84; P=0.01). Conclusions Revascularization of the RCA system with the RITA was associated with superior late survival when compared with SVG. This supports the view that, the use of RITA to graft the RCA should be encouraged especially in patients with long life expectancy.