Prevention of acute inducible atrial flutter in dogs by using an ibutilide-polymer-coated pacing electrode

Ibutilide – recent molecular insights and accumulating evidence for use in atrial flutter and fibrillation

Ibutilide is a 'pure' class III antiarrhythmic drug, used intravenously against atrial flutter and fibrillation. At a cellular level it exerts two main actions: induction of a persistent Na+ current sensitive to dihydropyridine Ca2+ channel blockers and potent inhibition of the cardiac rapid delayed rectifier K+ current, by binding within the channel pore cavity upon channel gating. Ibutilide has been shown to terminate atrial flutter and fibrillation in animal studies, with some risk of ventricular pro-arrhythmia. Experimental models of hypertrophy/heart failure show altered sensitivity to ibutilide, with increased dispersion of repolarisation and incidence of pro-arrhythmia. Patient trials show that ibutilide is effective at terminating atrial arrhythmias when given alone, and that it can increase effectiveness and reduce energy requirements of electrical cardioversion. The risk to patients of polymorphic ventricular tachycardia necessitates careful patient selection and monitoring during and after treatment. An ibutilide analogue, trecetilide, requires further investigation but may offer a less readily metabolised and pro-arrhythmic alternative to ibutilide.

Experimental models of atrial fibrillation/flutter

Animal models that mimic disease states or abnormal physiological events are tools that assist the investigator to understand the mechanism responsible for pathophysiological conditions. Atrial arrhythmias have intrigued physicians and cardiologists for decades. Thus the development of animal models for the study of atrial arrhythmias facilitate the investigation of these abnormal rhythms. Moreover, as our understanding of arrhythmias advances, so does the therapy designed to correct the condition, which ultimately improves the patient's clinical outcome. This manuscript describes a variety of animal models that have been utilized for the exploration of atrial arrhythmia generation and maintenance, as well as models used to evaluate the efficacy of putative antiarrhythmics agents.