Risk Stratification Using Mitral INsufficiency Echocardiographic Score 2 in Dogs With Preclinical Mitral Valve Disease

Background: Outcome-based cardiac risk stratification schemes are lacking for preclinical myxomatous mitral valve disease (MMVD). The Mitral INsufficiency Echocardiographic (MINE) score was developed as an easy-to-use severity classification of MMVD. Hypothesis/objectives: The primary aim was to verify the efficacy of the MINE score in stratifying the cardiac risk in preclinical MMVD. Secondary aims were to evaluate a simplification of the original score and propose a definition of "advanced B2". Animals: Seven hundred forty-nine dogs with preclinical MMVD. Methods: Retrospective, multicenter, cohort study. Clinical usefulness of the MINE score was tested by evaluating its association with median time to cardiac event. The Cox proportional hazards regression was used to evaluate the echocardiographic independent predictors of cardiac endpoint. Long-term outcome was analyzed using Kaplan-Meier curves and log-rank test. Results: Based on multivariate analysis, a simplified version of the MINE score was redefined including only the left atrium-to-aorta ratio, the left ventricular end-diastolic diameter, and the E-wave velocity. Mild cases had longer median time to cardiac event [2604 days, 95% confidence interval (CI) 2344-2604 days] in comparison to moderate (1216 days, 95% CI 998-1882 days) and severe cases (718 days, 95% CI 599-980 days; p < 0.001). Among stage B2, severe cases had shorter median time to cardiac event (718 days, 95% CI 599-980 days) in comparison to moderate (1141 days, 95% CI 980-1725 days) and mild cases (not available; p < 0.001). Conclusions and clinical importance: For this study cohort, the simplified version of the MINE score was clinically effective for risk stratification of preclinical MMVD. Dogs in stage B2 classified as "severe" can be defined "advanced" B2.