Current #guidelines recommend the mitral inflow/LVOT VTI ratio as an easy-to-measure semiquantitative index for isolated primary MR (>1.4 severe, <1 mild). But how robust is the evidence behind it? Let's take a closer look at this widely cited parameter. #EchoFirst Part 1 The mitral inflow/LVOT VTI ratio was first introduced as a semiquantitative parameter for grading primary mitral regurgitation in the 2013 EACVI #recommendations. This recommendation was based on the original study by Christophe Tribouilloy et al., published in 1994. Part 2