Epicardial pacemaker implantation in a young cat with sick sinus syndrome

A one-year-old Abyssinian cat was referred for episodes of vacancy, exaggerated blinking, and intermittent collapse episodes. A 12-lead electrocardiogram (ECG) and ECG telemetry demonstrated sinus bradycardia, sinus pauses, and sinus arrest with a junctional escape rhythm. No infectious agents were identified as a cause of the bradyarrhythmia during systemic disease screening. Findings were consistent with idiopathic sick sinus syndrome. Theophylline therapy did not improve clinical signs or ECG findings. An epicardial pacemaker was placed, which alleviated clinical signs. Pacemaker interrogation after implantation showed minimal use of the pacemaker. This case report highlights the utility of ECG telemetry in describing electrocardiographic findings of sinus arrest, a junctional escape rhythm, and sinus bradycardia in a cat with clinical signs, consistent with sick sinus syndrome which resolved following epicardial pacemaker implantation.