0.5☐.1 s, p=0.02) of spontaneous arrhythmias prior to any stimulation were significantly higher in the IVA rats.Ĭonclusion: This study demonstrates for the first time that chronic ivabradine administration is significantly proarrhythmic in healthy rats. More importantly, rare spontaneous arrhythmias were also recorded prior to any stimulation. After the stimulation protocols, the number of spontaneous atrial arrhythmias was similar in control and IVA rats (p=0.22), but mean duration of atrial arrhythmias was significantly longer in the IVA rats (1.7☐.3 vs. Overall arrhythmia inducibility was 26.2% in the IVA group and 17.9% in the control group (RR=1.3, 95%CI 1.1-1.5, p=0.01). On the first day of stimulation, 39.4% of the stimulation cycles were followed by arrhythmias in the IVA group and 17.2% in the control group (RR=1.8, 95%CI 1.3-2.5, p<0.01). Results: Rats in the IVA group presented significantly lower heart rates both before (299☒7 vs. 72-h continuous ECG monitoring was performed in freely moving rats before and after the stimulation protocols, and the number and duration of spontaneous atrial tachyarrhythmia episodes were determined.
First day and overall arrhythmia inducibility was assessed. Nine control and five IVA rats were then submitted to transesophageal pacing (4000 stimuli/min for 20 s 15 cycles) for 5 consecutive days. All rats were implanted with radiotelemetry ECG devices. Ivabradine (10 mg/kg/day) was administered in the drinking water for three consecutive weeks. Methods: Healthy male Wistar rats were randomized into two groups: Control (n=13) and treated with ivabradine (IVA n=15). Purpose: We aimed to assess the effect of chronic ivabradine administration on atrial arrhythmogenesis in in vivo, healthy rats. Data from clinical studies point towards an increased risk of atrial arrhythmias in ivabradine-treated patients, whereas in vitro experimental studies seem to indicate rather antiarrhythmic effects. Introduction: The effects of the If current blocker ivabradine on atrial arrhythmogenesis remains controversial.