Use of procainamide for conversion of acute onset AF following pericardiocentesis in a dog

A 9 yr old spayed female golden retriever was evaluated for anorexia and suspected gastric dilatation. Subsequent evaluation the following day determined the dog to have pericardial effusion. Muffled heart sounds and jugular pulses were noted on physical exam, and the dog was diagnosed with pleural and pericardial effusion. A sinus rhythm with a rate of 142 beats/min was documented on a surface electrocardiogram (EKG). Following pericardiocentesis, the heart rate increased to 260 beats/min, the rhythm became irregular, and the systemic blood pressure decreased. Atrial fibrillation (AF) was confirmed by EKG. Procainamide was administered IV over 15 min, resulting in successful conversion of AF to sinus rhythm and clinical improvement. Procainamide is one of several antiarrhythmic medications that are used for the conversion of acute AF in humans; however, its utility and efficacy in dogs in the setting of AF has not previously been reported. This case highlights a unique complication of performing a pericardiocentesis that requires immediate treatment and describes a potential treatment option for the conversion of acute AF in dogs.