Naturally occurring torsades de pointes and QT interval prolongation in a domestic cat.

A 10-year-old male American Shorthair cat was presented after a witnessed syncopal event. A Holter monitor demonstrated a long QT interval and revealed a rhythm characteristic of torsades de pointes (TdP) coincident with a bout of syncope. On subsequent Holter monitor recordings, sotalol did not prolong the QT interval further and did not reduce the severity of the underlying ventricular tachyarrhythmias, but no TdP was identified. When another syncopal event occurred, sotalol was discontinued, and oral amiodarone and magnesium were started. This resulted in improvement in the ventricular tachyarrhythmia. No syncopal events occurred in the ensuing 3 months, but the cat died of an unrelated disease shortly after. This is the first report of naturally occurring torsades de pointes in a domestic cat.