['Piceatannol, a hydroxystilbene natural product, has been reported to exert antiarrhythmic action via INa inhibition and slow INa inactivation in ischemia-reperfused (IR) rat hearts. The present study aimed to clarify the proarrhythmic property of piceatannol during regional IR injury in failing rabbit hearts.', 'Heart failure (HF) was induced by rapid right ventricular pacing for 4 weeks. The IR model was created by coronary artery ligation for 30 min, followed by reperfusion for 15 min in vivo. Simultaneous voltage and intracellular Ca(2+) (Cai) optical mapping was then performed in isolated Langendorff-perfused hearts (n=11 in each HF and control group). Action potential duration (APD) restitution, arrhythmogenic alternans and VF inducibility were evaluated by a dynamic pacing protocol. Conduction velocity was measured along lines across the IR and non-IR zones during pacing. Piceatannol (10 μM) was administered after baseline studies.', 'In the HF group, piceatannol decreased conduction velocity, induced rate-dependent regional inhomogeneity of conduction delay and wavelength shortening, slowed Cai decay, and facilitated arrhythmogenic alternans instead of APD prolongation to increase VF inducibility. In the control group, the proarrhythmic effects of piceatannol on APD restitution, arrhythmogenic alternans and conduction delay were offset by its antiarrhythmic effects (APD and wavelength prolongation), resulting in a neutral effect on VF inducibility.'] Does piceatannol facilitate conduction block and ventricular fibrillation induction in ischemia-reperfused rabbit hearts with pacing-induced heart failure?