Sotalol and flecainide dual therapy in a dog with paroxysmal atrial fibrillation.

A four-year-old Dobermann Pinscher was diagnosed with atrial fibrillation (AF) and equivocal dilated cardiomyopathy phenotype. Electrical cardioversion (ECV) was performed following two weeks of amiodarone treatment; however, the dog developed recurrent AF within one-week post-ECV. Following two additional months of amiodarone therapy, the dog represented with sinus rhythm and new hepatopathy. In-hospital electrocardiographic monitoring identified paroxysmal AF during sleep. Amiodarone therapy was transitioned to sotalol therapy, which prevented further paroxysmal AF episodes. However, episodes of atypical AFL were frequently observed during sleep at follow-ups over five months. Flecainide was added to the sotalol therapy, and no further occurrence of AF or AFL was observed at follow-ups over ten months. This report highlights that dogs may present with paroxysmal AF post-ECV. When the paroxysmal AF is likely vagally mediated, sotalol and flecainide dual therapy may be effective in preventing further occurrence of AF and AFL.