Resting and Exercise Cardiovascular Magnetic Resonance Imaging for the Assessment of Mitral Regurgitation

Background Mitral regurgitation (MR) is a heterogeneous disease requiring accurate investigations to guide optimal management. Cardiovascular magnetic resonance (CMR) provides reference standard biventricular assessment and highly reproducible MR quantification. Exercise-CMR (Ex-CMR) combines CMR with physiological stress; further development may allow comprehensive MR assessment. Therefore CMR is ideal to assist clinical decision making and assess research outcomes. Aims The thesis aims were to: 1) Develop and validate an Ex-CMR protocol assessing biventricular volumes and great vessel flow in healthy volunteers, 2) Evaluate the validated Ex-CMR protocol in primary MR patients, 3) Compare cardiac reverse remodelling and residual MR post mitral valve repair (MVr) vs replacement (MVR) in primary MR patients 4) Assess cardiac reverse remodelling after percutaneous mitral valve intervention for primary MR. Methods 1) Free-breathing, respiratory navigated Compressed-SENSE short-axis cines and aortic/pulmonary phase contrast magnetic resonance sequences were validated against clinical sequences at rest and used during Ex-CMR in 12 healthy volunteers, 2) 10 primary MR patients underwent the validated Ex-CMR protocol, 3) Of 83 moderate-severe primary MR patients, 72 (30 MVr, 22 MVR, 20 controls) completed CMR imaging at baseline and 6 months after mitral surgery or observation (control group). 4) Of 11 primary MR patients, 10 completed CMR imaging at baseline and 6-months after percutaneous intervention. Findings 1) Biventricular volumes and great vessel flow assessment during continuous supine Ex-CMR is feasible in healthy volunteers using the Compressed-SENSE Ex-CMR protocol, demonstrating good/excellent intra/inter-observer reproducibility, 2) The validated Ex-CMR protocol is feasible in asymptomatic primary MR patients demonstrating effective forward left ventricular ejection fraction is augmented by decreases in MR, 3) MVR results in comparable cardiac reverse remodelling to MVr with lower residual quantitated MR and better right ventricular ejection fraction (compared with controls) 4) In primary MR, percutaneous valve intervention results in MR reduction and positive left-ventricular reverse remodelling.