Systematic bilateral internal mammary artery grafting: lessons learned from the CATHolic University EXtensive BIMA Grafting Study

OBJECTIVES: Despite claims of feasibility, to date no study has examined the effect of systematic bilateral internal mammary artery (BIMA) use in a large cohort of real-world unselected patients. The CATHolic University EXtensive BIMA Grafting Study (CATHEXIS) registry was designed to assess the feasibility and safety of systematic BIMA grafting. METHODS: The CATHEXIS was a single-centre, prospective, observational, propensity-matched study. The study was supposed to include 2 arms of 500 patients each: a prospective arm and a retrospective arm. The prospective arm included almost all patients referred for coronary artery bypass grafting (CABG) at our institution after the start of the CATHEXIS with very few exceptions. BIMA would have been used in all these patients. The retrospective arm included patients submitted to CABG before the start of the CATHEXIS and propensity matched to the prospective group (average BIMA use 50%; the radial artery was extensively used). Safety analyses were scheduled after enrolment of 200, 300 and 400 BIMA patients. RESULTS: After the first 226 patients, the BIMA use percentage was 88.5% (200 of 226). In 178 (89%) patients, mammary arteries were used as Y graft. Postoperative mortality was 2%, and incidence of perioperative myocardial infarction, graft failure and sternal complications were 3.5%, 3% and 5.5%, respectively. No perioperative stroke occurred. The incidence of major adverse cardiac events (particularly graft failure and sternal complications) in the BIMA arm were significantly higher than those in the propensity-matched cohort; the study was stopped for safety. CONCLUSIONS: In a real world setting the systematic use of BIMA was associated with a higher incidence of perioperative adverse events (particularly sternal complications). Individualization of the revascularization strategy and use of alternative arterial conduits are probably preferable to systematic use of BIMA.