Background: Mitral regurgitation (MR) is the second most frequent valve disease in the developed world and accurate assessment of MR severity and its complications are important. With its excellent accuracy and reproducibility, cardiovascular magnetic resonance (CMR) imaging is an ideal tool to quantitatively assess MR severity and its cardiac remodelling in various clinical settings. Aims: The aims of the thesis were to 1) Assess the impact of MR severity on cardiac reverse remodeling and patients' outcome in the TAVI population 2) Assess the impact of mitral valve (MV) repair versus MV replacement on cardiac reverse remodelling 3) Evaluate the feasibility and reproducibility of a navigated image acquisition method for biventricular physiological assessment during continuous physical exercise 4) Evaluate the feasibility of exercise CMR (exCMR) in patients with significant MR Methods: 1) 85 patients undergoing TAVI with CMR pre- and 6m post-TAVI were evaluated 2) Of 65 patients with significant MR, 37 patients (9 MV repair, 10 MV replacement and 18 medical management) with paired CMR scans at baseline and 6-months were evaluated 3) 10 healthy volunteers underwent exCMR on two separate occasions using a free-breathing, multi-shot, navigated, balanced steady-state free precession cine pulse sequence 4) 12 patients with significant degenerative MR underwent navigated exCMR. Findings: 1) Significant MR is common in patients undergoing TAVI and improves in the majority post-procedure. Improvement in MR was not associated with more favourable LV reverse remodelling and baseline MR severity was not associated with mortality 2) MV surgery leads to positive atrial and left ventricular reverse remodelling. In this small series, MV replacement with chordal preservation has similar cardiac reverse remodelling benefits to MV repair 3) The navigated exCMR protocol allows simultaneous biventricular physiological assessment during continuous exercise. Intra- and inter-observer reproducibility were excellent 4) The navigated exCMR protocol is feasible in clinical patients with significant MR.