Left atrial decompression in dogs with heart failure secondary to myxomatous mitral valve disease: a long-term outcome study.

INTRODUCTION/OBJECTIVES: Left-sided congestive heart failure (CHF) secondary to myxomatous mitral valve disease carries high morbidity and mortality in dogs. Left atrial decompression (LAD) has been employed in severely affected dogs refractory to medical therapy, but long-term outcomes have not been reported. The aim of this study was to evaluate survival time following LAD, the frequency of iatrogenic atrial septal defect closure, the frequency of right-sided CHF, and the frequency of cardiac-related hospitalizations. ANIMALS, MATERIALS AND METHODS: A total of 111 client-owned dogs with stage B2, C, or D mitral valve disease undergoing LAD. A retrospective cohort study of patients treated between October 2018 and September 2021 was conducted. The primary outcome was time to cardiac-related death or euthanasia. Secondary outcomes included time to right-sided CHF, iatrogenic atrial septal defect closure, and frequency of CHF-related hospitalization. RESULTS: Iatrogenic atrial septal defect closure occurred in 22 dogs (20.2%), most commonly when septal puncture was performed caudal to the fossa ovalis. Forty-seven dogs (42.3%) developed right-sided CHF after LAD, with onset ranging from 1 to 873 days. Twenty-five dogs (22.5%) were hospitalized for cardiac disease after the procedure. Median survival time was 379 days (range, 1-1282) after the LAD procedure. STUDY LIMITATIONS: Given the retrospective design and absence of a medically managed control group, prospective studies are warranted to further define the long-term benefits of LAD. CONCLUSIONS: Left atrial decompression provided satisfactory survival times in dogs with advanced mitral valve disease refractory to standard therapy. Left CHF recurrence requiring hospitalization was uncommon, but right-sided CHF developed frequently, albeit with variable onset. Atrial septal defect closure was rare and may be minimized by puncturing within the fossa ovalis.