Review
Functional Mitral Regurgitation: Current Understanding and Approach to Management

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Abstract

Functional mitral regurgitation (FMR) is a challenging clinical entity that frequently complicates ischemic and nonischemic cardiomyopathy. The underlying pathophysiology of FMR is caused primarily by ventricular and subvalvular apparatus dysfunction which causes failure of proper leaflet coaptation. Echocardiography is the primary modality used in diagnosis and characterization of FMR. Echocardiography allows for assessment of valvular and ventricular structures and their interaction. FMR portends a poor prognosis, because it is frequently associated with increased morbidity and mortality. The optimal management of FMR involves an individualized approach that incorporates medical therapy and consideration of surgical, percutaneous, and resynchronization therapies according to the severity of regurgitation, presence of symptoms, option for revascularization, and the degree of ventricular remodelling.

Résumé

La régurgitation mitrale fonctionnelle (RMF) est une entité clinique complexe qui nuit fréquemment à la cardiomyopathie ischémique et non ischémique. La physiopathologie sous-jacente à la RMF est principalement causée par le dysfonctionnement des appareils ventriculaire et sous-valvulaire qui entraîne l’échec d’une bonne coaptation des feuillets. L’échocardiographie est la principale modalité utilisée pour le diagnostic et la caractérisation de la RMF. L’échocardiographie permet l’évaluation des structures valvulaires et ventriculaires, et leur interaction. La RMF laisse présager un mauvais pronostic puisqu’elle est fréquemment associée à l’augmentation de la morbidité et de la mortalité. La prise en charge optimale de la RMF implique une approche individualisée, qui comprend le traitement médical, et la considération de traitements chirurgicaux, percutanés et de resynchronisation, en fonction de la gravité de la régurgitation, de la présence de symptômes, de l’option de revascularisation et du degré de remodelage ventriculaire.

Section snippets

Epidemiology

Because distortion of LV geometry and function are key components in FMR, it is not surprising that FMR is common in ischemic and nonischemic cardiomyopathy. The prevalence of moderate to severe FMR has been reported to be up to 60% in ischemic cardiomyopathy and in 40% of cases of nonischemic cardiomyopathy.4, 5 Interestingly, FMR is now the leading cause of mitral regurgitation in the United States.5

FMR is an independent risk factor for death and admission to hospital. When using the proximal

Pathophysiology

Traditionally FMR has been described as a structurally normal mitral valve with impaired function due to ventricular dilation and dysfunction. However, new insights in to myocardial adaptation have also demonstrated abnormalities in the mitral leaflets. Indeed FMR is not simply a disease of ventricular dysfunction and might be better understood in terms of ventricular, subvalvular, and valvular interaction and adaptation.7, 8, 9

Insufficient mitral leaflet adaptation

Although LV dilatation and related perturbations of the subvalvular mitral apparatus are accepted causes of FMR, these conditions alone do not explain why the severity of mitral regurgitation varies in patients with similar degrees of leaflet tethering. Recent advances in 3-D echocardiography have demonstrated an increase in mitral leaflet tissue as an adaptive response to chronic leaflet tethering and morphologic LV changes in dilated, ischemic, and valvular cardiomyopathies. In a study in a

History and physical examination

History and physical examination are insensitive for the diagnosis of FMR. Symptomatology of FMR includes dyspnea on exertion, fatigue, and reduced exercise capacity. These are nonspecific symptoms; for example, all are also found in LV dysfunction. Furthermore, physical examination might be unreliable for the presence of a mitral regurgitant murmur, because the decreased LV pressures result in lower pressure gradients and a murmur that is often low-pitched and soft.24

Echocardiography

Echocardiography is the

Treatment

The management of FMR is challenging and controversial; there is considerable debate and uncertainly regarding the optimal approach, indications, timing, and effectiveness of interventions.2, 10 Treatment options include medical treatment, CRT, and surgical and percutaneous interventions.

Conclusions

FMR, a common complication of ischemic and nonischemic cardiomyopathy is associated with increased morbidity and mortality. LV remodelling, apical displacement of the papillary muscles, tethering of mitral leaflets, and deformation of the mitral annulus all result in decreased closing forces, leaflet malcoaptation, and regurgitation of blood into the LA. Although medical therapy is the foundation of treatment for FMR it is usually insufficient. Although CRT has shown some survival benefit, it

Disclosures

The authors have no conflicts of interest to disclose.

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