Prevalence and Prognostic Importance of Pulmonary Hypertension in Dogs with Myxomatous Mitral Valve Disease

Abstract BACKGROUND: Pulmonary hypertension (PH) is common in dogs with myxomatous mitral valve disease (MMVD) but its effect on clinical outcome has not been investigated. HYPOTHESIS/OBJECTIVES: The presence of PH worsens the outcome in dogs with MMVD. To compare survival times of dogs with MMVD and PH to those without PH. ANIMALS: Two hundred and twelve client-owned dogs. METHODS: Case review study. Medical records of dogs diagnosed with ACVIM stage B2 and C MMVD between January 2010 and December 2011 were retrospectively reviewed. Long-term outcome was determined by telephone interview or from the medical record. End of the observation period was March 2013. PH was identified if tricuspid regurgitation peak velocity was >3 m/s. RESULTS: Two hundred and twelve were identified. Eighty-three dogs (39%) had PH. PH was more commonly identified in stage C compared to B2 (P < .0001). One hundred and five (49.5%) dogs died during the observation period. Median survival time for the entire study population was 567 days (95% CI 512-743). Stage C (P = .003), the presence of PH (P = .009), left atrial to aortic root ratio (LA/Ao) >1.7 (P = .0002), normalized left-ventricular end-diastolic diameter (LVEDn) >1.73 (P = .048), and tricuspid regurgitation pressure gradient (TRPG) >55 mmHg (P = .009) were associated with worse outcomes in the univariate analyses. The presence of TRPG >55 mmHg (HR 1.8 95% CI 1-2.9; P = .05) and LA/Ao > 1.7 (HR 2 95% CI 1.2-3.4; P = .01) remained significant predictors of worse outcome in the multivariate analysis. CONCLUSIONS AND CLINICAL IMPORTANCE: In dogs with MMVD, moderate to severe PH worsens outcome.