Updated pathophysiological overview of functional MR (ventricular and atrial)

Area of Science:

• Cardiology
• Cardiac Surgery
• Biomedical Engineering

Background:

• Ventricular functional mitral regurgitation (FMR) is primarily caused by subvalvular tethering due to left ventricular (LV) and mitral valve (MV) annular dilatation.
• Standard surgical annuloplasty often fails to address subvalvular tethering, leading to persistent or recurrent FMR.
• Recent research highlights the potential protective role of mitral valve leaflet tissue growth against LV remodeling in ventricular FMR.

Purpose of the Study:

• To elucidate the distinct mechanisms of ventricular and atrial functional mitral regurgitation.
• To investigate the implications of subvalvular tethering and MV leaflet adaptation in ventricular FMR.
• To emphasize the newly recognized significance of atrial FMR and its association with heart failure.

Main Methods:

• Review of existing literature on the pathophysiology of ventricular and atrial functional mitral regurgitation.
• Analysis of the impact of LV remodeling and MV annular dilatation on subvalvular structures.
• Examination of recent findings on MV leaflet tissue growth and its role in mitigating FMR.

Main Results:

• Ventricular FMR is characterized by papillary muscle displacement and MV leaflet tethering, often inadequately treated by annuloplasty alone.
• Mitral valve leaflet tissue growth may offer a protective mechanism against ventricular remodeling and FMR.
• Atrial FMR, previously underestimated, is now recognized as a significant contributor to heart failure, even at moderate severity.

Conclusions:

• Novel therapeutic strategies for ventricular FMR may involve addressing subvalvular tethering and promoting MV leaflet adaptation.
• Atrial FMR warrants more aggressive clinical attention and potentially revised surgical indications due to its association with severe heart failure.
• Further research is crucial to understand the underlying mechanisms and optimize treatment for both types of functional mitral regurgitation.