Objectives: The aim of this study was to explore the predictors of the improvement in moderate ischaemic mitral regurgitation (IMR) after off-pump coronary artery bypass grafting (OPCAB) focusing on left ventricular (LV) dyssynchrony.Methods: A prospective study was performed among 135 patients (age at surgery, mean ± SD: 67.0 ± 8. 2 years, 33.3% women) with prior myocardial infarction and moderate IMR undergoing OPCAB from 2008 to 2015. Preoperative and follow-up clinical and echocardiographic parameters were analysed, focusing on LV global/regional dyssynchrony. Patients were grouped by IMR at 1 year postoperatively: improved group with no or mild IMR (n = 61) and failure group with moderate or severe IMR (n = 67). Data were compared between groups to explore the predictors of IMR improvement after OPCAB.Results: Seven patients who died before the 1-year postoperative assessment were excluded. At the 1-year follow up, there were 61 patients in the improved group and 67 patients in the failure group. Preoperatively, the improved group had smaller LV global dyssynchrony, LV regional dyssynchrony (papillary muscle systolic dyssynchrony; improved group versus failure group: 48.5 ± 4.5 ms vs 57.1 ± 3.9 ms; P