Chapter 36: Mitral Valve Repair: Rheumatic

INTRODUCTION

After recovery from an initial episode of rheumatic fever, approximately 60 to 65% of patients will develop heart valve disease (rheumatic heart disease, RHD) and possibly secondary conditions such as atrial fibrillation, endocarditis, and heart failure.¹ Rheumatic heart disease is one of the leading noncommunicable diseases in developing countries with a global prevalence of up to 19.6 million in 2005 and an incidence of 282,000 new cases per year.²

In Western countries, economic and sociopolitical changes together with prophylactic initiatives led by the American Heart Association and the World Heart Federation contributed to eliminate rheumatic fever by the 1980s (current prevalence in the United States is 0.05/1000). Much of the morbidity and mortality due to RHD has been proven to be effectively prevented by secondary prophylaxis including long-acting penicillin, oral anticoagulants, and surgical interventions.³ However, the costs of prophylaxis continue to burden low-income and middle-income countries as well as certain concentered populations of higher-income countries (demographic shifts due to immigration).⁴ In this context, an estimated of up to 468,164 patients die each year from RHD and or its clinical complications. Interestingly, recent echocardiographic data have shown that the true prevalence of the disease is significantly higher than the current global estimate if we take into consideration subclinical RHD.⁵

Rheumatic heart disease is unarguably the most common cardiovascular disease among individuals aged <25 years worldwide, and has a peak age group of 25 to 35 years (female predominance) in developing countries⁶ (Fig. 36-1). Conversely, patients with RHD in industrialized countries are either old (mostly above 50 years of age) or young immigrants. In this setting, the mitral valve is affected in 50% of patients and results in mitral regurgitation, mitral stenosis, or both.⁷ In younger patients, mitral regurgitation is predominant, but mitral stenosis becomes more prevalent with age and calcification of tissues. Regurgitant mitral valves are edematous with fibrotic thickening, and annular dilatation and anterior leaflet pseudoprolapse are often seen, whereas stenotic mitral valves present with stiff, nonpliable, and severely restricted leaflets, fusion of the subvalvular apparatus and commissures and often annular calcification⁸ (Fig. 36-2). Clinical assessment and two-dimensional echocardiography are paramount to detect and assess mitral stenosis, particularly in asymptomatic patients.⁹