Chronic mitral regurgitation treatment

# Overview
The distinction between primary nd secondary mitral regurgitation (MR) is of utmost importance when determining the treatment strategies among patients with chronic MR.  Primary and secondary MR have a different underlying pathophysiology and therefore have different indications for surgery and medical therapy. Surgery is generally the treatment of choice among patients with chronic primary MR and left ventricular systolic dysfunction; nevertheless, medical therapy is warranted when surgery is delayed or not planned.  The cornerstone of the treatment of patients with chronic secondary MR with decreased ejection fraction is the standard regimen for the treatment of heart failure, which includes one or more of the following: beta blockers, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, or aldosterone antagonists.  Mitral valve surgery is indicated in some circumstances among patients with chronic severe secondary MR, particularly those undergoing coronary artery bypass graft or patients with NYHA class III/IV heart failure symptoms.

# Medical Therapy of Chronic Mitral Regurgitation

## Primary Chronic Mitral Regurgitation
In MR, left ventricular systolic dysfunction and subsequent heart failure might occur.  Surgery is generally the treatment of choice among MR patients with left ventricular systolic dysfunction; nevertheless, medical therapy is warranted when surgery is delayed or not planned.
Although the body of literature for medical therapy in MR is not robust, the existing sparse data suggests that patients with MR who experience left ventricular systolic dysfunction are candidate for the standard therapy of heart failure, which includes beta blockers, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, or aldosterone antagonist.  Beta blocker use is associated with improved left ventricular function.
The administration of vasodilator is useful among patients with acute severe MR and those who have hypertension.  The benefits of vasodilator use in asymptomatic patients with normal blood pressure is not established, and might even be associated with worsening of the severity of MR.  The administration of vasodilators in this category of MR patients is therefore not recommended.

## Secondary Chronic Mitral Regurgitation
The valvular abnormality in chronic secondary MR results from the left ventricular dysfunction.  Therefore, the cornerstone of the treatment of patients with chronic secondary MR with decreased ejection fraction is the standard regimen for the treatment of heart failure which includes one or more of the following: beta blockers, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, or aldosterone antagonists.
Patients with coronary artery disease should receive treatment for their atherosclerosis disease.
Symptomatic patients with chronic severe secondary MR are candidate for cardiac resynchronization therapy with biventricular pacing.

# Surgical Therapy for Chronic Mitral Regurgitation

## Indications for Surgery in Chronic Primary Mitral Regurgitation
Shown below is an algorithm depicting the indications for mitral valve surgery or period monitoring among patients with chronic primary MR according to the 2014 AHA/ACC guideline for the management of patients with valvular heart disease.  Note that when mitral valve surgery is indicated, mitral valve repair is preferred over mitral valve replacement whenever feasible.
Abbreviations: LVEF: left ventricular ejection fraction; LVESD: left ventricular end systolic diameter; MR: mitral regurgitation; PASP: Pulmonary artery systolic pressure

## Indications for Surgery in Chronic Secondary Mitral Regurgitation
Shown below is an algorithm depicting the indications for mitral valve surgery or period monitoring among patients with chronic secondary MR according to the 2014 AHA/ACC guideline for the management of patients with valvular heart disease.  Note that when mitral valve surgery is indicated, mitral valve repair is preferred over mitral valve replacement whenever feasible.
Abbreviations: MR: mitral regurgitation

## Why the Mitral Valve is Replaced Before Symptoms in Patients with Chronic Mitral Regurgitation
- Mitral regurgitation is a syndrome of pure volume overload whereas aortic regurgitation is a combination of both volume and pressure overload.
- Both syndromes are associated with an increase in preload.
- In mitral regurgitation, the afterload is reduced whereas in aortic regurgitation the afterload is increased. This is very important because when the mitral valve is repaired, there is no longer a reduction afterload and the left ventricle may fail due to an abrupt rise in the afterload.  In aortic regurgitation, because the afterload is already increased chronically, replacement of the valve is not as likely to precipitate acute left ventricular failure due to an abrupt rise in afterload.
- By the time symptoms develop, there is already left ventricular dysfunction.
- Because of the low pressure system into which the blood is ejected into through the mitral valve, the ejection fraction is always high in mitral regurgitation. If the ejection fraction appears to be "normal", there is already decline in left ventricular function.
- There is no indication for vasodilator therapy in the absence of systemic hypertension in asymptomatic patients with preserved left ventricular function.

## Mitral Valve Repair vs Mitral Valve Replacement
There are two surgical options for the treatment of mitral regurgitation: mitral valve replacement and mitral valve repair.  In general, mitral valve repair is preferred to mitral valve replacement as it carries a lower risk of subsequent prosthetic valve endocarditis and results in better preservation of left ventricular function.

### Scenarios Favoring Mitral Valve Repair
- The ACC/AHA 2008 guidelines recommend mitral valve repair rather than mitral valve replacement if the anatomy is appropriate, including patients with rheumatic mitral valve disease and mitral valve prolapse (Grade 1C). The procedure should be performed at experienced surgical centers.
- Limited damage to certain areas of the mitral valve leaflets or chordae tendineae
- Limited calcification of the leaflets or annulus
- Prolapse of less than one-third of either leaflet
- Pure annular dilatation
- Valvular perforations
- Incomplete papillary muscle rupture

### Scenarios Favoring Mitral Valve Replacement
- Extensive calcification or degeneration of a leaflet or annulus
- Prolapse of more than one-third of the leaflet tissue
- Extensive chordal fusion, calcification, or papillary muscle rupture
- Extensive damage of mitral valve secondary to endocarditis

# 2020 AHA/ACC Focused Update of the 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease (VHD)

## 2020 Recommendations for Chronic Primary Mitral Regurgitation (MR) Intervention

## Indications for Intervention in Asymptomatic Severe Primary Mitral Regurgitation

## 2020 Recommendations for Chronic Secondary Mitral Regurgitation (MR) Intervention

## Indications for Mitral Valve Intervention in Secondary Mitral Regurgitation (MR)

# 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease: Executive Summary (DO NOT EDIT)

## Recommendations for Chronic Primary Mitral Valve Regurgitation

## Recommendations for Chronic Secondary Mitral Valve Regurgitation

# 2008 and Incorporated 2006 ACC/AHA Guidelines for the Management of Patients with Valvular Heart Disease (DO NOT EDIT) 

## Mitral Valve Surgery Indications (DO NOT EDIT) 

## Mitral Valve Surgery in Adolescents (DO NOT EDIT)