Abstract: Background: Quantitative assessment of mitral regurgitation (MR) severity has become increasingly important as surgical and catheter-based therapies for MR reduction become available.
Hypothesis/Objectives: Obtain quantitative measures of MR severity across stages of degenerative mitral valve disease (DMVD) and evaluate agreement between two methods.
Animals: 51 client-owned dogs stratified across three stages of DMVD (ACVIM B1, B2, and C).
Methods: Regurgitant volume (RVol) and fraction (RF) were measured on echocardiograms prospectively acquired by a single cardiologist by using Simpson’s method of discs (volumetric) and proximal isovelocity surface area (PISA) methods. RVol and RF were compared by both methods across disease stage (Kruskall-Wallis, Conover). Agreement between methods over the range of MR severity was determined by Bland-Altman analyses. Intra- and inter-observer measurement variability assessments were made via intraclass correlation coefficients (ICC).
Results: RVol was different (p< 0.0001) across stage by both volumetric (B1-0.09 mL/kg; B2-1.49 mL/kg; C-2.72 mL/kg) and PISA (B1-0.39 mL/Kg; B2-1.67 mL/kg; C-3.1 mL/kg) methods. Similarly, RF was different (p< 0.0001) across stage by both volumetric (B1-13.6%, B2-55.6%, C-67.2%) and PISA (B1-34.3%, B2-58.8%, C-75.2%) methods. Bias between volumetric and PISA for RVol (0.24 mL/kg) and RF (13.7%) was biologically acceptable, however the limits of agreement were wide. Proportional bias between methods was not present for RVol (p=0.79) or RF (p=0.53). Aside from PISA RF, intra- and inter-observer variability assessments showed ICC greater than 0.81.
Conclusions and clinical importance: Measurement of RVol and RF provide relevant information on MR severity across ACVIM stages of DMVD. Volumetric and PISA methods are not interchangeable.
