Repolarization and refractoriness in patients with persistent atrial fibrillation.

The use of monophasic action potential (MAP) recordings has been of important value during atrial fibrillation to understand the possibility of local pacing capture during the arrhythmia, while MAP and refractoriness determination after sinus rhythm restoration have highlighted the issue of electrophysiological remodeling owing to rate. Moreover the contemporary recording of MAP and refractoriness at the same atrial sites permitted to better understand the behavior of the ERP/MAP ratio in these patients. Local atrial pacing capture has been demonstrated in humans with chronic atrial fibrillation and suggests the presence of re-entrant circuits with large excitable gaps. The studies about atrial remodeling have shown a shortening of atrial ERP or monophasic action potential duration after cardioversion of persistent AF, while discordant results have been observed for what it concerns refractoriness adaptation to rate. Finally, the recording of a mean ERP/MAP90 ratio < 1 at all the pacing cycle lengths, indicates that no post-repolarization refractoriness was present after cardioversion of persistent atrial fibrillation.