Repolarization and refractoriness in patients with persistent atrial fibrillation

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Arrhythmias

Background:

• Monophasic action potential (MAP) recordings are crucial for understanding atrial fibrillation (AF).
• MAP and refractoriness assessment post-sinus rhythm restoration reveals electrophysiological remodeling due to heart rate changes.
• Simultaneous MAP and refractoriness recordings clarify the ERP/MAP ratio in AF patients.

Purpose of the Study:

• To investigate local pacing capture during AF.
• To analyze atrial remodeling and refractoriness adaptation to rate after cardioversion.
• To evaluate the ERP/MAP ratio in patients with persistent AF after rhythm restoration.

Main Methods:

• Utilizing monophasic action potential (MAP) recordings.
• Determining refractoriness after restoring sinus rhythm.
• Performing local atrial pacing during AF.
• Recording MAP and refractoriness at identical atrial sites.

Main Results:

• Local atrial pacing capture in humans with chronic AF suggests re-entrant circuits with large excitable gaps.
• Studies indicate shortened atrial effective refractory period (ERP) or MAP duration after cardioversion of persistent AF.
• Discordant results were observed regarding refractoriness adaptation to rate.
• A mean ERP/MAP90 ratio < 1 at all pacing cycle lengths signifies no post-repolarization refractoriness post-cardioversion.

Conclusions:

• MAP recordings provide valuable data on atrial electrophysiology during AF and after rhythm restoration.
• Atrial remodeling, specifically ERP shortening, occurs after cardioversion of persistent AF.
• The ERP/MAP ratio is a key indicator of refractoriness and post-repolarization phenomena in AF patients.