Superiority of bilateral internal thoracic artery grafting in long-term survival after coronary artery bypass through the lenses of a bedside risk score

Objective Risk algorithms for the prediction of long-term survival after coronary artery bypass grafting (CABG) do not include the use of bilateral internal thoracic artery (BITA) grafting among the independent predictors. We sought to reveal the superiority of BITA grafting in the long-term outcome through the lenses of an existing bedside risk score (BRS). Methods This study analyzed data from 5,666 consecutive patients undergoing isolated (n = 4,715 – BITA = 2,792) and combined (n = 951 – BITA = 246) CABG. The mean follow-up period was 10.3 years (interquartile range, 9.9 years). All the predictors of an existing BRS were available for analysis (age, body mass index, ejection fraction, unstable hemodynamic state, left main disease, cerebrovascular disease, peripheral arterial disease, congestive heart failure, malignant ventricular arrhythmia, chronic obstructive pulmonary disease, diabetes, and previous heart surgery). Furthermore, a modified BRS was constructed taking into account the use of BITA grafting and combined CABG. Results The good discriminatory ability and satisfactory calibration of the BRS was confirmed in the isolated CABG subgroup. The modified BRS showed improved discriminatory ability and similar calibration. It showed a time-varying coefficient, and accordingly, we calculated the adjusted survival predictions up to 20 years after isolated and combined CABG with or without BITA grafting. Patients with BITA grafting in the low-risk quartile showed 68.4% and 65.5% predicted survival rates at 20 years in the isolated and combined CABG subgroups, respectively, versus the survival rates of 56.4% and 52.8% observed among patients without BITA grafting. Conclusion The modified BRS is a useful simplified algorithm for clinicians in choosing treatment intervention for severe isolated or combined coronary artery disease. We clearly demonstrated the superiority of BITA grafting in long-term survival throughout the entire range of the modified BRS.