Role of Medical Therapy in Chronic Mitral Regurgitation

*Ruchika Meel*

## **Abstract**

Mitral regurgitation is one of the most commonly encountered valvular heart diseases in both the developing and the developed world. From various studies, it is known that chronic mitral regurgitation is associated with progressive left ventricular dysfunction, and eventually death if left untreated. This disease has a long silent period before symptoms manifest. During this latent period, left ventricular function progressively deteriorates and results in poor outcomes for patients even if surgery is performed. A few studies have evaluated the role of medical therapy in patients with chronic mitral regurgitation. This chapter will provide an overview of the use of medical therapy in chronic mitral regurgitation.

**Keywords:** chronic mitral regurgitation, medical therapy

#### **1. Introduction**

In heart failure (HF), irrespective of aetiology, there is activation of the sympathetic nervous system and the renin angiotensin system that initially serves as compensatory mechanism to maintain the falling cardiac output through retention of sodium and water, peripheral arterial vasoconstriction and increased cardiac contractility [1–3]. However, long term stimulation of these systems has a deleterious effect and results in cardiac remodelling and eventually irreversible HF in the absence of therapy [2, 4]. In HF due to chronic mitral regurgitation (MR) the aforementioned mechanisms are activated and over time result in apoptosis, necrosis and myocyte slippage and left ventricular (LV) remodelling and dilatation from loss of interstitial collagen [3]. There are a number of studies that have evaluated the effects of drugs in degenerative MR. Most of these involved beta blockers or vasodilators. The pathophysiologic basis for their use was to prevent the deleterious effect of sympathetic nervous system in MR, and medical therapy decreased afterload and LV wall stress, thus preventing deleterious remodelling [5].

In this review chapter a brief overview of aetiology and pathophysiology of MR will be provided, followed by the current perspective regarding the value of medical therapy in chronic MR will be discussed.

#### **2. Definition and aetiology of mitral regurgitation**

Chronic MR is a result of abnormality of the one or more of the components of the mitral valve apparatus [3, 6]. Mitral regurgitation can be a result of abnormality of mitral leaflet, chordae tendineae, papillary muscles and annulus. It can be

**Figure 1.**

*(A) Parasternal long-axis view depicting an eccentric anteriorly directed mitral regurgitation jet secondary to restricted posterior mitral leaflet motion. (B) Parasternal long-axis view depicting a contemporary patient with established rheumatic heart disease: thickened shortened chordae, restricted posterior mitral leaflet [7].*

primary or secondary. Primary MR is confined to de novo abnormality of the mitral leaflet itself, whereas secondary MR is as a result of another disease process usually involving the LV, which results in a regurgitant mitral valve. Mitral regurgitation results in volume overload of the LV and culminates in left ventricular failure if left untreated.

There are numerous aetiologies of mitral regurgitation [6]. The common cause of MR in the developed world is due to degenerative disease and in the developing world MR is due to rheumatic heart disease (**Figure 1**). Other causes of MR include: infective endocarditis, trauma, drugs, congenital heart disease and annular calcification. Secondary mitral regurgitation is due to coronary artery disease, cardiomyopathies (dilated, hypertrophic cardiomyopathy) and right ventricular pacing.
