Functional Mitral Regurgitation: Epidemiology, Risk Stratification, Outcomes, and Novel Transcathether Therapies

Abstract

Mitral regurgitation is the most common valvular heart disease in developed countries, increasing in prevalence alongside the ageing population and expanding burden of contributory diseases such as AF, HFpEF and hypertension.

Significant mitral regurgitation is associated with heart failure, reduced quality of life and premature death, and represents a substantial burden of disease and major healthcare expenditure.

The approach to mitral valves that have become regurgitant as a consequence of extra-valvular structural or functional cardiac abnormalities is complicated and nuanced; FMR represents a heterogeneous group of conditions that remain, relative to primary / degenerative mitral regurgitation (DMR), less well-understood and clinically recognised. Treatment options to date have thus been comparatively limited in breadth and in efficacy when compared to DMR, evidenced by the relatively minimal guideline-directed therapy for FMR.

This thesis focuses attention on FMR, exploring subtypes, outcomes, prognosis and interventions through the objectives below, with the intention of expanding the understanding of this very common yet complex collection of conditions.

1. Investigate the prevalence of atrial functional mitral regurgitation (AFMR) in the world’s largest database of adult patients undergoing echocardiogram (the National Echocardiographic Database of Australia - NEDA).

2. Define and test a method of stratifying risk in FMR that can be clinically utilised to plan timing of intervention and inform discussions around prognosis.

3. Interrogate the popular theory of mitral regurgitation severity to left ventricular dilatation ‘proportionality’ in FMR as a predictor of response to transcatheter mitral valve repair through systematic review and meta-analysis.

4. Present 12 month outcomes data from a world-first clinical trial on a novel transcatheter mitral valve repair device that expands the therapeutic armamentarium available for treatment of FMR.