Causes of non-functioning right internal mammary used in a Y-graft configuration: insight from a 6-month systematic angiographic trial.

Objective: Y-graft configuration with left and right ITA (RITA) allows complete arterial revascularisation. We previously compared two types of ITA revascularisation in a prospective randomised trial with a systematic 6-month angiographic follow-up study. The present study is a secondary analysis of these populations to evaluate the angiographic parameters influencing the function of the RITA used in a Y-graft configuration.
Methods: The functionality of the RITA was based on the TIMI grade flow: in TIMI grade 0 (occluded graft) and in TIMI grade 1 or 2 (balanced flow), the RITA was considered not functional. RITA was considered functional when a complete opacification (TIMI 3) of all anastomoses of the targeted coronary vessels was observed.
Results: A total of 25.3% of RITA were not functional. In univariate analysis, the number of anastomoses, the type and size of grafted coronary segments and the severity of the native coronary stenosis influenced ITA function. In multivariate analysis, the function of the RITA was positively influenced by the number of anastomoses (OR=0.5, 95% CI: 0.4-0.7), and a severely narrowed first circumflex (OR=39.1, CI: 8.1-189.2) and negatively by the presence of a grafted intermediate coronary artery (OR=0.01, CI: 0.003-0.06), and of a grafted RCA (OR=0.08, CI: 0.02-0.35). The size of targeted vessel, history of infarction and regional myocardial function did not influence ITA function.
Conclusions: In this systematic angiographic study, the function of the RITA used as a Y-graft was significantly improved when used on several branches of the circumflex artery or on a severely narrowed first circumflex. Grafting of the intermediate branch or of a RCA has a negative prognostic influence on graft function.