Proarrhythmic electrical remodelling is associated with increased beat-to-beat variability of repolarisation.

Objective: Acquired long-QTsyndrome in combination with increased beat-to-beat variability of repolarisation duration (BVR) is associated with lethal torsades de pointes arrhythmias (TdP) in dogs with remodelled heart after atrioventricular block (AVB). We evaluated the relative contributions of bradycardia and ventricular remodelling to proarrhythmic BVR with and without pharmacological IKr block in order to identify the individual at risk. Methods: Three groups of dogs were used: sinus rhythm dogs (n=12), dogs with acute AVB (n=8), and dogs with >3 weeks chronic AVB (n=27). Under anaesthesia, ECG and monophasic action potential duration (MAPD) were measured. Local BVR was quantified as short