Left Ventricular Ejection Fraction in Mitral Regurgitation Because of Flail Leaflet
It has long been understood that left ventricular ejection fraction (LVEF) is a poor measure of LV systolic function because of load dependence, measurement error, and observer variability. In addition, LVEF, which is calculated from end-diastolic and end-systolic chamber volumes, is really a measure of chamber function not myocardial function. These issues are particularly problematic in mitral regurgitation (MR), where favorable loading conditions can preserve LVEF even when cardiomyocytes demonstrate loss of contractile elements and abnormal mitochondria.1 More sophisticated measures of LV systolic function, such as end-systolic elastance2 and arterial-elastance coupling,3 are of value in MR but are complicated and time-consuming and have not been adopted into clinical practice. Despite its flaws, LVEF remains important in MR because it is widely available and easy to measure. Both the American4 and European5 guidelines indicate that asymptomatic patients should be considered for mitral valve surgery before LVEF falls <60%, particularly when the anatomy is suitable for mitral valve repair. In addition, guidelines suggest that once LVEF falls <30%, the risks of mitral valve surgery might outweigh its benefits. These guidelines are based on expert opinion (Level of Evidence C) because there are limited data to support specific LVEF cutoff values in MR.
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In this issue of Circulation: Cardiovascular Imaging, Tribouilloy et al6 report the relation of LVEF to outcomes in a large series of 1875 patients with MR because of flail leaflet in the Mitral Regurgitation International Database (MIDA) registry. Flail leaflet is a common manifestation of degenerative MR, is a known predictor of outcome,7 and usually is associated with severe MR.8 Only patients in sinus rhythm at the time of index echocardiography …