Asymptomatic mitral regurgitation: when to operate?

The timing of surgical intervention in asymptomatic or mildly symptomatic patients with mitral regurgitation has always been a difficult clinical dilemma, especially with current options of valve replacement or valve repair. Symptomatic status should be carefully assessed and may depend upon either atrial fibrillation or progressive left ventricular dysfunction. Many patients may claim to be asymptomatic, but have profound limitations to their functional capacity and impairment of contraction indices. Because of this, every effort should be made to objectively follow the asymptomatic patient and schedule surgical intervention before irreversible left ventricular dysfunction. Left ventricular ejection fraction continues to be an inappropriate parameter, for the regurgitant fraction increases the preload to the left ventricle, and the regurgitant orifice reduces left ventricular afterload with increase to the left ventricle, and the regurgitant orifice reduces left ventricular afterload with increase in ejection fraction. End-diastolic dimension of volume is dependent upon such preload, and hence not accurate. End-systolic diameter is a better prognostic index; an end-systolic dimension of 4.5 cm (2.6 cm/m2) and a calculated end-systolic volume of 50 mL/m2 seem to be reasonable discriminators of outcome following surgery. More recent investigations suggest that left ventricular dP/dt, measured from a Doppler profile of mitral regurgitation, is perhaps a better predictor. In the asymptomatic patient, it is difficult to justify a role for intense medical therapy. The patient who develops atrial fibrillation does require a long-term anticoagulation therapy, and valve repair might be considered in this patient. Sinus rhythm may be restored with early surgical intervention, thereby reducing complications of thromboembolism or anticoagulant therapy.(ABSTRACT TRUNCATED AT 250 WORDS)