Very long-term outcome of bilateral internal thoracic artery in diabetic patients: a systematic review and reconstructed time-to-event meta-analysis

Introduction: Benefits of single (SITA) and bilateral internal thoracic arteries (BITA) in diabetics undergoing coronary bypass grafting (CABG) are conflicting. We undertook a study-level meta-analysis to compare early and long-term outcomes of both CABG configurations. Methods: PubMed, CENTRAL and EMBASE were searched for studies comparing BITA versus SITA for isolated CABG surgery in diabetics. Randomized trial or observational studies were considered eligible for the analysis. Kaplan-Meier curves of long-term survival were reconstructed and compared with Cox linear regression; incidence rate ratios (IRR) with 95% confidence intervals (CI) for long-term survival were calculated. Landmark analysis and time-varying hazard ratio (HR) were analyzed. Odds ratios (OR) were extracted for early mortality, postoperative stroke, deep sternal wound infection (DSWI), and myocardial infarction (MI). A random effects meta-analysis was performed. Sensitivity analyses included leave-one-out-analyses and meta-regression. Results: Thirteen studies (7,332 patients) were included. Overall, at 20-year follow-up, BITA was associated with higher survival (HR=0.77; 95% CI, 0.71-0.84; p<0.0001). Time-varying HR and landmark analysis reported BITA was associated with higher rate of 10-year survival (HR=0.75, 95% CI 0.68-0.82, p<0.0001), while from 10-20-year follow-up no difference was revealed (HR=0.99, 95% CI 0.82-1.19, p=0.93). There was no increase in early mortality, postoperative MI, stroke or DSWI between the groups. At meta-regression, the higher the age, the higher the long-term overall survival in patients with BITA. Conclusions: In diabetics, the BITA approach is associated with improved 10-year survival with no increase in early mortality, MI, stroke or DSWI. In the 10-20-year timeframe, BITA and SITA showed comparable survival.