Left Atrial Strain at Different Stages of Myxomatous Mitral Valve Disease in Dogs.

BACKGROUND: Decreased function of the left atrium (LA) is a useful prognostic indicator in dogs with myxomatous mitral valve disease (MMVD). In humans, LA strain is a novel severity indicator of mitral regurgitation, but its clinical utility in dogs has not been confirmed.

OBJECTIVES: To examine whether LA strain as evaluated with speckle-tracking echocardiography is associated with MMVD stage in dogs.

ANIMALS: Fifty-two client-owned dogs with MMVD.

METHODS: Cross-sectional study. Dogs were classified as stage B1, B2, C, or D, according to the American College of Veterinary Internal Medicine consensus. Physical examination findings and echocardiographic variables were compared among the groups. To assess the comparative accuracy of echocardiographic variables in identifying dogs with the presence or history congestive heart failure (CHF), receiver operating characteristic curves and multivariate logistic analysis were used.

RESULTS: There were no significant differences in parameters of LA strain between B1 and B2 groups. However, LA longitudinal strain during atrial contraction (εA ) (median, 19.1%; interquartile range, 15.3-24.3% in B1, 19.6%; 14.1-21.4% in B2, 6.2%; 3.18-11.2% in C/D) and during ventricular systole (εS ) (32.7%; 28.9-39.2% in B1, 35.6%; 31.7-41.9% in B2, 23.6%; 16.9-26.1% in C/D) were significantly lower in stages C/D than in stages B1 and B2. In multivariate logistic regression analysis, εA and peak early diastolic mitral inflow velocity were identified as independent indicators of stage C/D.

CONCLUSIONS AND CLINICAL IMPORTANCE: εA was the best predictor of the presence or history of CHF. Further studies are needed to determine the clinical implications of these findings for treatment decisions and prognosis determination.