Introduction

Mitral regurgitation (MR) is the most commonly diagnosed valvular disorder[1], accounting for approximately one-third of acquired left-sided valve pathology in developed countries.[2] MR is classified broadly as primary or secondary. Primary MR results from pathologic abnormalities including myxomatous degeneration, rheumatic heart disease, radiation injury, endocarditis, and autoimmune disease. Secondary MR, also known as functional MR (FMR), occurs when the valve leaflets are structurally normal, but leaflet coaptation is restricted by abnormal structure and/or function of the left ventricle (LV). FMR is more common, and has a worse prognosis than primary MR. Etiologies of FMR include ischemic and nonischemic cardiomyopathy, and rarely isolated LA enlargement.[3] Because the underlying pathology in FMR is due to LV dysfunction and resultant congestive heart failure (CHF), the value of surgical correction of FMR is debated and remains controversial. Even mild FMR can be harmful to patients with CHF, as FMR has been shown to be both a sign of advanced CHF and an independent determinant of CHF death. As a result, FMR severity impacts quality of life as well as survival; however, evidence about the prognostic implications of surgically correcting FMR remains scarce. This chapter will focus on assessment, management, and treatment of FMR in the setting of CHF.