Echocardiographic indices and severity of mitral regurgitation in dogs with preclinical degenerative mitral valve disease.
BACKGROUND
Describing severity of mitral regurgitation (MR) in dogs with degenerative mitral valve disease (DMVD) is challenging.


HYPOTHESIS/OBJECTIVES
Mitral regurgitant fraction (RF), effective regurgitant orifice area (EROA), and the ratio of mitral regurgitant to aortic flow (QMR :QAo ) can be calculated from routine echocardiographic measurements and provide additional information regarding MR severity.


ANIMALS
Fifty-seven dogs with preclinical DMVD including 36 without and 21 with cardiomegaly.


METHODS
Prospective observational study. The expected relationships among RF, EROA, and QMR :QAo and 1-dimensional measurements including left atrium to aortic root diameter ratio (LA:Ao) and normalized left ventricular internal dimension at end-diastole (LVIDdN) were mathematically derived and calculated using echocardiographic data from the study population. Nonlinear goodness of fit was determined by calculation of the root mean standard error. The correlations between 1-dimensional and multidimensional indices were analyzed using receiver operating characteristic curves.


RESULTS
The relationships among RF, EROA, QMR :QAo , and both LA:Ao and LVIDdN were curvilinear, and the multidimensional indices differentiated MR of variable severity. By contrast, 1-dimensional measurements were insensitive to MR severity until RF equaled or exceeded 50%. Regurgitant fraction ≥50%, EROA to body surface area ≥0.347 and QMR :QAo ≥0.79 were strongly associated with LA:Ao ≥1.6 and LVIDdN ≥1.7.


CONCLUSIONS AND CLINICAL IMPORTANCE
Regurgitant fraction, EROA, and QMR :QAo quantify MR severity in dogs with preclinical DMVD in a manner that 1-dimensional measurements do not.
['Larouche-Lebel|Éva|É|', 'Loughran|Kerry A|KA|', 'Oyama|Mark A|MA|https://orcid.org/0000-0002-5218-9226']
D000818:Animals D004283:Dog Diseases D004285:Dogs D004452:Echocardiography D005260:Female D006349:Heart Valve Diseases D008297:Male D008943:Mitral Valve D008944:Mitral Valve Insufficiency D012720:Severity of Illness Index
degenerative mitral valve disease regurgitant fraction heart disease myxomatous degeneration