ReviewFunctional Mitral Regurgitation: Current Understanding and Approach to Management
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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