Katharyn J. Mitchell

Summary Accelerated idioventricular rhythms (AIVR) are increasingly diagnosed in horses, particularly in those with underlying systemic disease. Recognition of these abnormal rhythms is important but specific treatment is often not necessary unless the rhythms become haemodynamically relevant, with AIVR often resolving as the systemic disease improves. The goals of treatment, when indicated, include improving cardiac output, decreasing systemic and myocardial inflammation (if present) and controlling the ventricular rate and rhythm. Identification of any persistent myocardial damage or arrhythmia burden will be important for the prognosis and risk assessment of these patients in the longer term.