Dr Kawa Haji( left) Cardiologist, interventional and structural fellow, Cardiology Department, Alfred Health, Melbourne, Victoria.

Professor Antony Walton( right) Interventional and structural cardiologist, deputy director of cardiology and director of cardiac laboratories, Cardiology Department, Alfred Health, Melbourne, Victoria.

First published online on 5 July 2024.

It was correct at the time of publication and was updated in December 2025.

BACKGROUND

MITRAL regurgitation( MR) is defined

as backward flow of blood from the left ventricle( see figures 1 and 2) into the left atrium during systole. 1 This is the most common valvular heart disease in Western countries, including Australia, and occurs particularly in ageing populations.

In the US, the prevalence of mitral valve( MV) disease is greater than 10 % in those older than 75 years, despite a reduction in the incidence of rheumatic heart disease, making it a significant public health issue. 2, 3 While those with MR may be asymptomatic early in the course of the disease, if left untreated, it can eventually lead to heart failure and death. 4

Recent advances in cardiac multimodality imaging and surgical techniques, as well as the introduction of transcatheter interventions into practice, have transformed the care provided to patients with MR and significantly improved outcomes. It is essential that this condition is detected early in the primary care setting to ensure patients with MR receive appropriate treatment.

This How to Treat provides an overview of the epidemiology, diagnosis and management of MR. It aims to equip GPs with the knowledge to identify patients early in the course of the illness and initiate a timely treatment plan, including early referrals to specialised valve centres.

AETIOLOGY

THE MV apparatus is a dynamic and complex structure consisting of the mitral annulus, the anterior and posterior leaflets, chordae tendinea, and papillary muscles surrounded by left ventricular and left atrial walls( see figure 3). 5

MV function is dependent on the appropriate interplay of these components. Disturbance in any part of this apparatus or surrounding structure can lead to MR. 6

To determine appropriate therapeutic approaches, guidelines classify MR into either primary or secondary. Primary MR is defined as a structural abnormality in any component of the MV apparatus causing MV leak, while secondary MR is defined as disease of the left

ventricle or left atrium that interferes with the integrity of the MV apparatus, thus causing a leak in the MV. 7

Primary mitral regurgitation

While rheumatic heart disease( see

figure 4) is a common cause of primary MR in low income and developing countries, the most common cause of primary MR in Western countries is degenerative disease affecting components of the MV apparatus, including myxomatous degeneration of the MV leaflets and / or redundant chordal apparatus. 8, 9

Redundant leaflets can prolapse back into the left atrium causing malcoaptation of the leaflets and consequent regurgitation. Degeneration and rupture of the chordae may lead to the MV becoming unsupported, which results in MR. Primary MR can also occur from leaflet perforation from pathologies like endocarditis. Other rare causes include drugs, radiation, and systemic disease-causing restricted leaflet motion from thickening of both leaflets and subvalvular apparatus. An additional recognised cause of MR

in the elderly population is mitral annular calcification, which may start in the posterior annulus and extend into the subvalvular apparatus, affecting leaflet function. 10

Secondary mitral regurgitation

The MV apparatus is normal in functional

or secondary MR; however, ventricular or atrial dilatation and / or remodelling leads to an imbalance in coaptation of the MV, which causes MR.

Ventricular dilatation from either ischaemic or nonischaemic cardiomyopathy, as well as markedly depressed or even normal left ventricle( LV) function after an isolated infero-basal myocardial infarction leading to posterior leaflet tethering, can lead to gradual annular dilatation and / or leaflet malcoaptation. 11 This begins a cycle of increasing LV pressure and volume overload, leading to further LV dilatation and remodelling with progressive dysfunction and worsening MR. 1

Secondary MR can also occur as a result of chronic atrial fibrillation that causes significant atrial