Long-Term Outcomes of Mitral Valve Repair With Artificial Chordae and Annuloplasty for Myxomatous Mitral Valve Disease in Dogs.

backgroundMyxomatous mitral valve disease (MMVD) in dogs commonly progresses to congestive heart failure, which carries a poor prognosis. Mitral valve repair (MVR) is a recognized treatment for advanced-stage MMVD. HYPOTHESIS/

objectivesIdentify the risk factors and prognosis in dogs undergoing MVR. ANIMALS: We enrolled 1019 dogs with MMVD (ACVIM stages B2, C, and D) that underwent MVR between January 2017 and December 2020.

methodsMedical records from a single institution were retrospectively reviewed. Early and late postoperative periods were defined as < 100 days and 100-1400 days after surgery, respectively. The outcome was time to a composite of all-cause mortality, onset of postoperative congestive heart failure, or undergoing a second MVR (surgical revision).

resultsIn the early postoperative period, 61 dogs experienced the composite outcome; in the late period, 211 dogs did. No dogs underwent a second MVR. The incidence rate was 19.6 and 7.1 events per 1000 dog-months in the early and late periods, respectively. Compared with stage B2 dogs, stage D dogs had 2.2 times the daily hazard of experiencing an early postoperative event. In the late period, increasing age (per year; hazard ratio [HR], 1.3), higher body weight (per kilogram; HR, 1.1), Cavalier King Charles Spaniels compared with Chihuahuas (HR, 2.2), and preoperative tricuspid valve regurgitant velocity > 3.7 m/s (HR, 2.5) were associated with the events. CONCLUSIONS AND CLINICAL IMPORTANCE: A higher incidence of the event was observed in the early postoperative period rather than later, with the outcome varying according to MMVD condition and patient-specific factors.