Subclinical left ventricular systolic dysfunction in chronic mitral regurgitation and its potential impact on management: quo vadis?

Mitral regurgitation (MR) is the second commonest valvular lesion prevalent in the community at large and its detection increases exponentially with advancing age.1 Primarily, MR is of two types: intrinsic valvular disease or organic MR and the functional MR (FMR). The latter is essentially a left ventricular (LV) disease, primarily ischaemic, with secondary and functional involvement of the mitral valve apparatus. The issue of managing FMR is far more complex and out of preview of the present discussion. It is the organic MR, and more so when it is asymptomatic, that the need and timing of intervention requires attention. Decision-making process requires knowledge about aetiology, mechanism of valve incompetence, and severity of MR. In the western world, major cause of MR is degenerative while in the developing countries, rheumatic heart disease continues to be an important aetiology along with mitral valve degeneration in older subjects. No large-scale data on the natural history of asymptomatic rheumatic MR are available, although such data are reported on degenerative MR.2–4 We do not know if what is true for degenerative MR applies to rheumatic MR as well. Degenerative MR is progressive while rheumatic MR severity may remain static for a long period due to relatively fixed valve.4 Also, sudden cardiac death in degenerative MR is a known unfortunate event related to the degree of LV dysfunction, severity of MR, and the type of valve involvement.5 All symptomatic organic MR patients require repair or replacement, unless, co-morbidities are the confounders. Hence, it is the asymptomatic patients with significant organic MR and some symptomatic patients with confounding co-morbidities who are the focus of attention with regard to necessity and timing of surgical intervention. Morphology of the mitral valve is an important issue as far as feasibility and success of mitral valve repair is concerned and hence, there may be and should be different parameters for guiding therapy in rheumatic MR which is usually not reparable.