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

Abstract

Background: Myxomatous 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/Objectives: Identify 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. Methods: Medical 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). Results: In 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.