The role of myocardial fibrosis in outcome following mitral valve repair in degenerative mitral regurgitation

Liu, Boyang (2020). The role of myocardial fibrosis in outcome following mitral valve repair in degenerative mitral regurgitation. University of Birmingham. Ph.D.

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Primary degenerative mitral regurgitation (MR) is a disease of increasing prevalence. Its optimal management is surgical repair, but surgery timings remain controversial. Current guidelines that suggest ‘watchful-waiting’ have been criticised for promoting rescue surgery after the establishment of symptoms or left ventricular (LV) dysfunction. Conversely, non-selective early surgical approaches result in unnecessary surgery for some patients.

Myocardial fibrosis has been hypothesised to accumulate in MR, leading to eventual overt LV dysfunction. This thesis examines this hypothesis, assesses the prognostic impact of myocardial fibrosis, and determines its value as a biomarker for optimising the timing of surgery.

In a prospective multicentre study of severe MR patients, I provide definitive histological evidence for the presence of myocardial fibrosis, before the onset of symptoms. Due to its patchy nature, non-invasive quantification of fibrosis on cardiac magnetic resonance (CMR) was a superior marker of preoperative myocardial function and symptom burden.

However, neither histology- nor CMR-derived fibrosis correlated with postoperative outcomes. Despite successful surgery, symptomatic patients continued to possess worse cardiopulmonary exercise (CPET) performance and symptom burden quantified via patient-response questionnaires (PROMs) compared to asymptomatic patients, providing additional support for the benefits of early surgery. Further evaluation of surveillance CPET and PROMs is indicated for patients in whom early surgery is clinically inappropriate.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Licence: All rights reserved
College/Faculty: Colleges (2008 onwards) > College of Medical & Dental Sciences
School or Department: Institute of Cardiovascular Sciences
Funders: British Heart Foundation


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