Modern Management of Mitral Stenosis

A lthough once rheumatic fever and its consequences were the major cause of valvular heart disease in the developed world, this disease has become exceedingly rare today.As a consequence, mitral stenosis (MS), which is usually caused by rheumatic fever, has also become rare.In fact, MS is most commonly found in the United States in patients who have emigrated here from areas where rheumatic fever is still endemic.Nonetheless, Ϸ1500 balloon mitral valvotomies (BMVs) were performed in the United States last year, which provides a rough index of severe disease prevalence.The following is a review of the current understanding and management of this disease. EtiologyAlthough the attack rate for rheumatic fever is roughly equal among genders, MS is 2 to 3 times more common in women.2]3 What factors cause susceptibility to the illness remain unclear.Likewise, factors responsible for the decline in MS incidence in developed countries are also obscure.Although the decline may be due in part to the introduction of antibiotics, a fall in the attack rate of rheumatic fever began well before antibiotics were widely available. 4nce begun, the rheumatic process leads to inflammation in all 3 layers of the heart: endocardium, myocardium, and pericardium.However, the disease primarily affects the endocardium, leading to inflammation and scarring of the cardiac valves.Although the process is punctuated by acute episodes of rheumatic fever, chronic inflammation and scarring continue well after the last attack, leading to severe valve damage years later.The mechanism of this chronic process is debatable and is thought to be due either to a continuing low-grade rheumatic process or to hemodynamic stresses on the now-injured valve.Elevated C-reactive protein levels, indicative of ongoing generalized inflammation, are found in many patients before BMV, which supports an inflammatory origin for MS. 5 Although all of the cardiac valves may be involved by the rheumatic process, the mitral valve is involved most prominently and in virtually all cases.Stenosis of this valve occurs from leaflet thickening, commissural fusion, and chordal shortening and fusion.Occasionally, mitral annular calcification rather than disease of the valve leaflets and chordae tendineae is the cause of mitral stenosis.Annular calcification appears to be closely related to aortic and aortic valve calcification, which have recently been associated with atherosclerosis rather than with rheumatic fever. 6Other exceedingly rare causes of MS include use of anorectic drugs and carcinoid syndrome.