Mitral valve regurgitation, or mitral insufficiency, is a condition in which the heart's mitral valve does not close completely causing blood to leak back into the left atrium. When signs and symptoms of mitral valve regurgitation develop, they may occur gradually because the heart is able to compensate for the valve defect. Mitral regurgitation is often first suspected when the doctor hears a heart murmur. Sometimes, however, the disorder develops quickly, and patients may experience an abrupt onset of more severe signs and symptoms such as shortness of breath, fatigue and cough, especially with exertion. Other symptoms and signs include heart palpitation, swollen legs, and excessive urination.
There are two basic types of mitral regurgitation: degenerative and functional. Degenerative mitral regurgitation is caused by damage to the leaflets of the mitral valve, whereas functional Mitral Regurgitation (FMR) occurs without any alteration of the structure of the mitral valve leaflets and is secondary to myocardial infarction or dilated cardiomyopathy. Left ventricular systolic dysfunction and enlargement can result in annular dilatation and papillary muscle displacement with consequent tethering of the mitral leaflets. These changes will not allow the valve to close tightly.
More than 3 million people in the United States suffer from moderate or severe mitral regurgitation, with more than 250,000 new patients diagnosed each year. FMR can be found in 84% of patients with congestive heart failure and in 65% of them the degree of regurgitation is moderate or severe. The long term prognostic implications of functional mitral regurgitation have demonstrated a significant increase in risk for heart failure or death, which is directly related to the severity of the regurgitation. Compared to mild regurgitation, moderate to severe regurgitation was associated with a 2.7fold risk of death and 3.2 fold risk of heart failure, and thus significantly higher health care cost.
Treatment of mitral valve regurgitation depends on the severity and progression of signs and symptoms. Left unchecked, mitral regurgitation can lead to heart enlargement, heart failure and further progression of the severity of mitral regurgitation. For mild cases, medical treatment may be sufficient. For more severe cases, heart surgery might be needed to repair or replace the valve.