Age cutoff for the loss of survival benefit from use of radial artery in coronary artery bypass grafting

Background: Controversy still exists about the superiority of the radial artery (RA) over the saphenous vein graft (SVG) as a second conduit for surgical myocardial revascularization. We aimed to investigate the presence of any survival benefit from use of the RA and relate it to patients' age. Methods: Propensity score matching was conducted on 9005 patients who underwent first-time isolated coronary artery bypass grafting (CABG) using the left internal thoracic artery at a single institution from 1996 to 2012. The use of RA was recorded in 936 patients, whereas the use of SVGs only was recorded in 8069 patients. The primary study end point was all-cause death. The interaction between patients' age and any survival benefit from the RA was assessed by spline analysis. Results: After propensity matching, the sample size consisted of 809 matched pairs. In the matched group, mean follow-up was 6.4 ± 3.6 years (range, 0-13.6 years). Survival was 96.8% ± 0.6% versus 96.0% ± 0.6% at 1 year, 91.4% ± 1.1% versus 90.1% ± 1.0% at 5 years, and 83.2% ± 1.7% versus 79.4% ± 1.9% at 10 years for patients receiving RA or SVG, respectively. RA use was associated with a lower risk for late death (hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.57-0.98; P = .03). However, the protective effect from RA on late survival was not equally present across all age groups, as shown by spline analysis. The survival advantage from RA was maximum in patients 60 years and younger (upper limit of 95% CI, <1) and gradually declined with increasing age, until it was no longer present in patients older than 70 years (adjusted HR, 0.90; 95% CI, 0.63-1.28; P = .57). Conclusions: The use of the radial artery graft as a second conduit improves all-cause mortality in patients undergoing primary isolated CABG up to the age of 70 years.