Outcomes of mitral valve repair in dogs with myxomatous mitral valve disease and preoperative atrial fibrillation.

Abstract

BACKGROUND: The surgical efficacy of mitral valve repair (MVR) in dogs with advanced myxomatous mitral valve disease (MMVD) and atrial fibrillation (AF) remains unclear. HYPOTHESIS/OBJECTIVES: To explore risk factors for the persistence of AF and to evaluate survival after MVR. ANIMALS: Twenty-eight dogs with preoperative AF selected from a cohort of 2733 dogs with MMVD that underwent MVR between January 2015 and April 2024. METHODS: This retrospective study evaluated whether AF persisted at 30 days postoperatively. Risk factors for postoperative persistent atrial fibrillation (pAF) were assessed using preoperative variables. Survival was analyzed using landmark analysis over 2 postoperative intervals: 0-30 days and 30-1000 days. RESULTS: Four dogs died within the first 30 days. Ten dogs were assigned to the pAF group, whereas 14 dogs that returned to sinus rhythm (SR) comprised the SR group. During the initial 30-day postoperative period, the survival probability at 30 days was 86% (95% confidence interval [CI], 74-100). Body weight (per 1.0 kg; risk ratio, 1.07; 95% CI, 1.01-1.12) and preoperative fractional shortening (per 1.0%; risk ratio, 0.95; 95% CI, 0.90-0.99) were predictive of postoperative pAF at 30 days. From 30 to 1000 days, the survival probability at 1000 days was 45% (95% CI, 20-100) in the pAF group and 90% (95% CI, 73-100) in the SR group (P = .030). CONCLUSIONS AND CLINICAL IMPORTANCE: Greater body weight and systolic dysfunction might be associated with postoperative pAF, which might negatively affect long-term survival after MVR.