Background: The prevalence and prognostic importance of atrial fibrillation (AF) on survival in nonsmall breed dogs with myxomatous mitral valvular disease (MMVD) and congestive heart failure (CHF) remain unknown.
Aim: To identify the prevalence of AF in nonsmall breed dogs with CHF because of MMVD and to characterize the impact of AF on survival outcome.
Animal: Sixty-four client-owned dogs (>15 kg) with MMVD and CHF.
Methods: Retrospective review of medical records for dogs weighing >15 kg with MMVD treated for CHF.
Results: Thirty-three dogs presented with AF or developed AF during follow-up examinations, and 31 dogs were free of AF until cardiac-related death. For dogs with AF, median survival time (MST) was 142 days (range: 9-478) while dogs without AF lived 234 days (range: 13-879 days). AF increased risk of cardiac-related death (HR = 2.544; 95% CI = 1.41-4.59; P = .0019) when compared to dogs without AF. MST was significantly prolonged for dogs with AF whose rates were adequately controlled (<160 bpm; 171 days; n = 13) when compared to dogs that failed to respond to negative chronotropic agents (61 days; n = 20; P = .032). The administration of combination treatment (diltiazem and digoxin) significantly decreased median HR to 144 bpm (range: 84-218 bpm) in dogs with AF and significantly prolonged MST (diltiazem+digoxin: 130 days versus diltiazem: 35 days, P = .0241) when compared to diltiazem alone.
Conclusions and clinical importance: Inadequately controlled AF is associated with a higher rate of mortality. Optimization of therapeutic strategies for the rate control of AF remains determined.
Keywords: Atrial fibrillation; Congestive heart failure; Myxomatous valvular disease; Prognosis.
Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.