High-rate pacing reduces variability of repolarization and prevents repolarization-dependent arrhythmias in dogs with chronic AV block.

Introduction: high-rate pacing may have an inhibitory effect on the initiation of Torsade de Pointes arrhythmias (TdP). However, permanent pacing is only indicated in high-risk patients. We performed a proof of concept study into automatic overdrive pacing for prevention of drug-induced TdP, using short-term variability of repolarization (STV) as a feedback parameter of arrhythmic risk.

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

Objective: Acquired long-QT syndrome 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 I(Kr) 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).