Effect of ectopic focus frequency on fibrillatory conduction in atrial remodelling tissue. A simulation study

Atrial fibrillation (AF) is the most common atrial tachyarrhythmia. Recently, pulmonary vein ectopic focus has been demonstrated that it can trigger reentry in the presence of a vulnerable substrate and lead to AF. We examined the effects of ectopic focus frequency on the generation of AF. In this study, the effects of remodelling on ionic currents were incorporated in a two-dimensional anisotropic model of human left atrial tissue. Ectopic activity initiated a stable reentry around the right pulmonary veins. The interaction of this ectopic activity with a rapid sinus rhythm generated fibrillatory conduction. This fibrillatory rhythm was maintained only at high rates of ectopic focus. Our study suggests that the interaction of high frequency ectopic activity and rapid sinus rhythm facilitates the progress from a stable reentrant mechanism to fibrillatory conduction in remodelling atrial tissue.