[How severe is mitral regurgitation? Possibilities and problems of echocardiographic evaluation in clinical practice]

: Echocardiography is the most commonly used technique for evaluating patients with mitral regurgitation (MR) and estimating MR severity. However, in clinical practice, echocardiographic assessment of MR severity remains challenging in many cases, particularly in patients with forms of intermediate or borderline severity. The main causes are the improper application of the echocardiographic methods for assessment of MR severity and the lack of a validated standardized approach for quantification of various types of MR, including organic and functional MR. In this review, we describe how best to use echocardiography for assessing MR severity in the light of current knowledge and guidelines