Pre-excitation alternans in a cat

A nine-year-old male neutered domestic shorthair cat presented on referral for evaluation. The cat presented to its primary veterinarian for acute onset vomiting, panting, and weakness. An electrocardiogram performed at the regular veterinarian was concerning for ventricular tachycardia, and the cat was referred for further evaluation. An echocardiogram revealed hypertrophic cardiomyopathy, and a review of the electrocardiogram revealed findings suggestive of ventricular pre-excitation alternans with the suspect pre-excited complexes appearing to alternate with sinus complexes. This is the first reported case of pre-excitation alternans in a cat.