Abstract: Background – Echocardiographic estimates of mitral (MAA) and aortic annular area (AAA) are used to calculate regurgitant volume. The accuracy of MAA and AAA in dogs with degenerative mitral valve disease (DMVD) are unknown. Hypothesis/Objectives – To determine the accuracy of echocardiographic estimates of MAA and AAA compared to planimetered annular area using cardiac computed tomography (CCT) in dogs with DMVD. Animals – Twenty dogs with ACVIM stage B2 DMVD. Methods – Observational study on dogs that underwent echocardiography and CCT on the same day. Echocardiographic mid-diastolic MAA was estimated from a right parasternal long-axis (RPLx) 4-chamber and left apical 4-chamber (AP4C) view. Echocardiographic early systolic AAA was estimated from a RPLx outflow and a left cranial (LCr) view. Annular area was estimated using the formula: diameter (leaflet hinge-points)2 x 0.785. Pearson’s correlation coefficients and Bland-Altman’s method were used to compare CCT and echocardiography. Results – Significant associations were identified when comparing AAA_RPLx (r=0.87, 95%CI=0.70, 0.95) and AAA_LCr (r=0.94, 95%CI=0.85, 0.98) to AAA_CCT and when comparing MAA_RPLx4C (r=0.86, 95%CI=0.68, 0.94) and MAA_AP4C (r=0.90, 95%CI=0.77, 0.96) to MAA_CCT. Bias and limits of agreement for AAA_RPLx (-0.29 [-0.80, 0.21] cm2) and AAA_LCr (-0.25 [-0.63, 0.13] cm2) were smaller compared to MAA_RPLx4C (-0.71 [-2.06, 0.63] cm2) and MAA_AP4C (-1.14 [-2.24, -0.05] cm2). All comparisons exhibited significant (P< 0.001) fixed bias. Conclusions/Clinical Importance – Echocardiographic estimates of annular area, particularly MAA, underestimated annular size compared to CCT. Indices of regurgitant volume utilizing MAA might be inaccurate in dogs with DMVD.
