Quantification of mitral regurgitation
The degree of severity of MR can be quantified by the regurgitant fraction, which is the percentage of the left ventricular stroke volume that regurgitates into the left atrium.
regurgitant fraction   =   
  
    
      
        
          
            
              
                V
                
                  m
                  i
                  t
                  r
                  a
                  l
                
              
              −
              
                V
                
                  a
                  o
                  r
                  t
                  i
                  c
                
              
            
            
              V
              
                m
                i
                t
                r
                a
                l
              
            
          
        
        ×
        100
        %
      
    
    {\displaystyle {\frac {V_{mitral}-V_{aortic}}{V_{mitral}}}\times 100\%}
  where Vmitral and Vaortic are, respectively, the volumes of blood that flow forward through the mitral valve and aortic valve during a cardiac cycle.