A Case of Heart Failure Secondary to Mitral Regurgitation

Case Study

A 70-year-old woman is admitted to a local hospital emergency department with acute chronic heart failure (HF) for the third time in the past year. She complains of increased swelling of her legs and abdomen for the past 4 weeks. This was preceded by palpitations lasting  a few minutes and occurring several times daily. She had been diagnosed with mitral valve prolapse as a teenager, and echocardiography performed 3 years earlier revealed her mitral regurgitation (MR) to be severe. She was referred to a cardiologist but did not follow up after being subsequently diagnosed with lymphoma. She was treated with chemoradiation 2 years ago and is currently in remission.

At baseline assessment prior to admission, she has symptoms of New York Heart Association (NYHA) class IV HF, progressed from NYHA class III 6 months earlier. Echocardiography shows an ejection fraction (EF) of 30% to 35% and left ventricular internal diameter in diastole of 45 mm with severe MR (regurgitant volume of 65 cc and regurgitant fraction of 60%).

How would you treat this patient?

Introduction

Mitral regurgitation is one of the most common valvular disorders and the most common regurgitant disorder¹ and leads to progressive left ventricular failure and death if untreated.² The Framingham Heart Study found a prevalence of mild to severe MR in 19% of the population, and its prevalence is increasing as the population ages.¹ Moderate to severe MR is the most commonly encountered valve disease in the United States and the second most common valvular disease requiring surgery in Europe.³ An estimated 2 to 2.5 million people in the United States were affected by moderate to severe MR in 2000, and this number is anticipated to double by 2030.³

Differentiation of the etiology of the disease is essential for prognosis and management. Primary or organic disease involves valve incompetence caused by intrinsic mitral valve disease of leaflets, chordae tendineae, papillary muscles, and/or annulus.  Most commonly, mitral valve prolapse and primary myxomatous degenerative disease cause organic MR in individuals the developed world.⁴ Less commonly, infective endocarditis, connective tissue disease, radiation-induced heart disease, and rheumatic heart disease (in conjunction with mitral stenosis) can cause clinically significant MR. Surgical repair in severe primary disease has been highly successful in preserving the left ventricle and reducing morbidity.⁵

In contrast, secondary MR is a functional disease precipitated by left ventricular dysfunction and disruption of the normal mitral valve anatomy. Repair remains controversial with less clear and consistent outcomes, as repair does not intervene on the primary mechanism of dysfunction.⁶ Causes of secondary MR include coronary artery ischemic disease and nonischemic dilated cardiomyopathy. In the developed world, the incidence of secondary MR is increasing relative to primary MR.⁷

Surgical repair of the mitral valve remains the gold standard treatment in severe MR and is preferred over valve replacement based on a number of observational studies.^2,8 Chronic, severe MR often remains asymptomatic for years due to compensatory mechanisms in the left atria and ventricle; however, once symptoms do develop, they usually reflect severe disease. Increased understanding of the progression and underlying pathophysiology of MR has led to more specific indications and improved outcomes for surgical repair.⁹ Early detection, management, and repair have been shown to improve both objective and quality-of-life outcomes.^10,11 Valve repair has been shown to be performed too infrequently for the prevalence of the disease and is frequently not even offered.⁷ This finding may reflect an aging population with increasing life expectancy and more comorbid illnesses.

Although surgery remains the gold standard, up to half of patients with indications for surgery will not qualify due to prohibitively high surgical risk.¹² Furthermore, surgical morbidity and mortality have remained at high levels despite the improvements mentioned above.² More recently, advancing percutaneous technologies have allowed the introduction of transcatheter repair of the mitral valve, particularly in a large number of high-risk surgical patients.¹³ Results of preliminary studies have been promising, although evidence remains limited and more study is required.