Aims: It remains unclear whether surgical or transcatheter mitral valve repair for secondary mitral regurgitation (MR) in patients with non-ischaemic cardiomyopathy reverse the underlying left ventricular (LV) pathophysiology. We hypothesized that mitral valve repair improves LV systolic function and forward flow and induces LV reverse remodelling in this group of patients.Methods and results: Seventy-six patients (65 ± 14 years old, 43% male) with non-ischaemic cardiomyopathy and moderate to severe chronic secondary MR treated successfully with transcatheter or surgical mitral valve repair were evaluated. Transthoracic echocardiography was performed at baseline, discharge and 6 months post-repair. After mitral valve repair, LVEF, and LV global longitudinal strain (GLS) corrected for LV end-diastolic volume remained unchanged over time (P = 0.90 and P = 0.96, respectively). In contrast, LV forward flow increased significantly over time (stroke volume index: from 20 ± 7 to 29 ± 8 and 26 ± 8 mL/m2, P < 0.001; cardiac index: from 1.50 ± 0.44 to 2.36 ± 0.60 and 2.01 ± 0.48 L/min/m2, P < 0.001). In addition, LV end-diastolic and end-systolic volume index significantly reduced over time (from 87 ± 42 to 70 ± 33 and 75 ± 39 mL/m2, P < 0.001; and from 60 ± 35 to 50 ± 30 and 53 ± 36 mL/m2, P = 0.004, respectively). These changes were independent of the type of repair.Conclusion: Surgical and transcatheter mitral valve repair for secondary MR in patients with non-ischaemic dilated cardiomyopathy improved LV forward flow and induced LV reverse remodelling but did not change LV systolic function.