Reversal atrial electrical remodeling following cardioversion of long-standing lone atrial fibrillation.

Background: Atrial fibrillation (AF) itself promotes electrophysiological changes, termed 'electrical remodeling', facilitating its recurrence and maintenance. There is evidence that the remodeling process is reversible after restoration of the sinus rhythm (SR). However, the timing for the recovery of electrophysiological properties is still undefined.

Objective: The aim of this study was to assess the atrial electrical activation using P-wave signal-averaged electrocardiogram (P-SAECG) post-cardioversion of long-standing AF, focusing on the reversal remodeling process to identify the timing of the process stabilization.

Methods: Subjects with lone persistent AF, eligible for cardioversion and successfully converted to SR, were enrolled at the study. SAECG was performed immediately after reversion to SR and repeated on days seven and thirty.

Results: Of 31 subjects, nine presented early recurrence of atrial fibrillation, all of them in the first seven days post-cardioversion; 22 remained in SR for at last one month and SAECG was obtained on days seven and thirty after cardioversion. In the latter, P-wave duration progressively abated from the first to the third SAECG (P-wave duration: 185.5+/-41.9 ms vs 171.7+/-40.5 ms vs 156.7+/-34.9 ms, respectively, first, second and third SAECG; p<0.001 for all matches). In the frequency domain analysis, spectral turbulence was not apparent in SAECG immediately post-cardioversion, but sharply increased on day seven and remained unchanged on day thirty.

Conclusion: This study suggests that the first seven days post-cardioversion of long standing AF are critical for reversal remodeling process and arrhythmia recurrence.