The Role of Myocardial Fibrosis in Degenerative Mitral Regurgitation
Research type
Research Study
Full title
A prospective observational study examining the role of myocardial fibrosis in outcome following mitral valve repair in degenerative mitral regurgitation.
IRAS ID
170435
Contact name
Richard Steeds
Contact email
Sponsor organisation
Birmingham Clinical Research Office, QEHB
Clinicaltrials.gov Identifier
Duration of Study in the UK
4 years, 0 months, 0 days
Research summary
Research Summary
In patients with severely leaking mitral heart valves (mitral regurgitation), blood leaks backwards every heart beat instead of being ejected out of the heart. The leak puts the heart under increased strain and over time causes the heart to enlarge and weaken. To prevent permanent damage, surgery may be recommended to repair the leaking valve. The timing of surgery remains controversial. Current international guidelines recommend surgery when a severe leak causes i) symptoms such as breathlessness or ii) dilatation of the heart or reduced pumping function on ultrasound scans (TTE)(. Recent studies have shown that the results of surgery at this stage may not result in complete recovery of the heart, leading some heart doctors to advocate surgery before symptoms develop or the heart enlarges. The disadvantage of this “early surgical” approach are the risks of open heart surgery when patients feel well. Also in some patients, symptoms and enlargement of the heart may take many years to progress allowing older patients to avoid surgery. Presently, doctors rely on TTE to monitor the heart but these scans often over-estimate the strength of the muscle when there is a leaky valve and are not sensitive enough to detect early changes in the heart muscle fibres. This means that some patients are operated on too late, and some may undergo surgery when it is not yet necessary. A preliminary study from our hospital has shown that cardiac magnetic resonance imaging (CMR) (which is non-invasive and involves no radiation) may be better at detecting early changes in heart function as well as scarring within the heart muscle. This scarring is present in at least a third of patients with leaky valves. We believe these patients might be better operated on earlier as more scarring may limit reoveery of the heart after surgery.
Summary of Results
Leakage of the mitral valve within the human heart (primary mitral regurgitation) can result in symptoms of heart failure.
Current European guidelines recommend watchful waiting until the onset of overt symptoms as patients are likely to remain symptom-free for many years despite possessing severe mitral regurgitation. In fact, data from one study suggests that 55% of severe mitral regurgitation patients are still free from symptoms after 8 years of follow-up. Therefore, early surgery before the onset of symptoms may place patients at unnecessary surgical risk.
However, other studies have shown that delaying surgery until after the onset of symptoms, results in poorer long-term outcomes even after successful surgery. This is likely due to the effects of a gradual scarring process within the heart muscle.
Our study aimed to 1) provide evidence for this heart muscle scarring process, 2) demonstrate that it can be quantified through a non-invasive technique, and 3) assess its influence on patient outcomes.
With the use of small biopsy samples, taken at the time of surgery, we demonstrated that heart muscle scar did indeed develop in symptom-free patients.
We demonstrate that this scar burden can be quantified non-invasively, before surgery, with heart MRI scans.
Finally, we report that MRI measures of scar burden, quantified before surgery, can influence the recovery of the heart following surgery.
Our results highlight the potential for heart MRI scans to select which symptom-free patients should receive surgical intervention early, and which patients can be treated via close observation, without surgery.
REC name
East Midlands - Nottingham 2 Research Ethics Committee
REC reference
15/EM/0243
Date of REC Opinion
2 Jun 2015
REC opinion
Further Information Favourable Opinion