Abstract
INTRODUCTION: Eleclazine is a highly selective late sodium current inhibitor, possibly effective in reducing ventricular fibrillation (VF) in heart failure (HF) with ischemia-reperfusion (IR) injury. The electrophysiological effects of eleclazine at therapeutic hypothermia (TH) are unknown. We investigated the effects of eleclazine in suppressing VF in failing rabbit hearts with IR injury undergoing TH. METHOD: HF was induced by right ventricular pacing. An IR model was created using coronary artery ligation for 60 min, followed by reperfusion for 30 min. Hearts were excised and Langendorff-perfused for optical mapping and electrophysiological studies. Electrophysiological studies were repeated after TH (33°C) for 30 min or eleclazine (1 μm) infusion for 20 min. RESULTS: In failing IR-injured hearts, eleclazine reduced action potential duration (APD) dispersion and accelerated intracellular Ca2+ uptake to suppress arrhythmogenic alternans but also exacerbated rate-dependent conduction slowing, resulting in neutral effects on VF inducibility at normothermia. TH increased VF severity. Eleclazine after TH ameliorated TH-induced APD dispersion and further depressed conduction to reduce VF inducibility and severity. TH after eleclazine also slowed conduction to a greater extent to reduce VF inducibility and severity by extrastimulus pacing. In control IR-injured hearts, eleclazine increased VF severity by dynamic pacing at normothermia, which was counteracted by TH. CONCLUSIONS: Eleclazine does not prevent VF at normothermia but reduces VF inducibility and severity by extrastimulus pacing at TH in isolated failing hearts with regional IR injury.