Bradyarrhythmias and Pacemaker Therapy in Dogs with Chagas Disease

Abstract

Chagas disease (Trypanosomiasis) is a cause of myocarditis in the southern United States causing cardiac conduction abnormalities, arrhythmias, and heart failure. To report clinical findings and outcome in Chagas positive (CP) dogs requiring pacemaker implantation for bradyarrhythmias. One hundred and forty-four client-owned dogs requiring pacemaker implantation. Retrospective case series. Information regarding history, physical exam, laboratory and diagnostic imaging findings, treatment, and survival were obtained from medical records, with additional follow-up information obtained by contacting referring veterinarians and owners. Of the 144 dogs requiring pacemaker implantation from January 2001 to May 2010, 83 (57.6%) had a Chagas titer performed and 9 (10%) were CP. Concurrent ventricular arrhythmias (odds ratio 1.61, P = .005) or atrioventricular (AV) block (odds ratio 4.18, P < .001) increased the likelihood that a Chagas titer was submitted. Median age for CP dogs was 6.2 years (range, 0.3-10); 7 were male. Bradyarrhythmias included high-grade 2nd or 3rd degree AV block (n = 8) and sinus bradycardia with 1st degree AV block (n = 1); 5 had concurrent ventricular arrhythmias. A positive Chagas titer had a negative impact on survival (hazard ratio 4.04; 95% CI 1.36-12.1, P = .012) with a reported median survival time of 365 days (interquartile range, 84-973 days). Bradyarrhythmias can result in clinical signs requiring pacemaker implantation in CP dogs, and although the diagnosis negatively impacts survival, pacemaker therapy is a viable treatment option.