Survival characteristics and prognostic variables of dogs with mitral regurgitation attributable to myxomatous valve disease

Background: There are few studies evaluating the natural history and prognostic variables in chronic mitral valve disease (CMVI) in a heterogeneous population of dogs. Objectives: To estimate survival and prognostic value of clinical and echocardiographic variables in dogs with CMVI of varying severity. Five hundred and fifty-eight dogs belonging to 36 breeds were studied. Methods: Dogs were included after clinical examination and echocardiography. Long-term outcome was assessed by telephone interview with the owner. Results: The mean follow-up time was 22.7 +/- 13.6 months, and the median survival time was 19.5 +/- 13.2 months. In univariate analysis, age > 8 years, syncope, HR > 140 bpm, dyspnea, arrhythmias, class of heart failure (International Small Animal Cardiac Health Council), furosemide therapy, end-systolic volume-index (ESV-I)> 30 mL/m(2), left atrial to aortic root ratio (LA/Ao)> 1.7, E wave transmitral peak velocity (Emax)> 1.2 m/s, and bilateral mitral valve leaflet engagement were associated with survival time when all causes of death were included. For the cardiac-related deaths, all the previous variables except dyspnea and EDV-I > 100 mL/m(2) were significantly associated with survival time. Significant variables in multivariate analysis (all causes of death) were syncope, LA/Ao > 1.7 m/s, and Emax > 1.2 m/s. For cardiac-related death, the only significant variable was LA/Ao > 1.7. Conclusions and Clinical Importance: Mild CMVI is a relatively benign condition in dogs. However, some clinical variables can identify dogs at a higher risk of death; these variables might be useful to identify individuals that need more frequent monitoring or therapeutic intervention.