Atrial fibrillatory rate and sinus rhythm maintenance in patients undergoing cardioversion of persistent atrial fibrillation.

The study set out to explore whether an index of atrial electrical electrophysiology can be used to predict atrial fibrillation (AF) relapse, and if the predictive properties differ as a result of arrhythmia duration. METHODS AND RESULTS: The study comprised 175 consecutive patients with persistent AF (median duration 94 days, range 2 to 1044) referred for cardioversion. Twenty-nine patients had arrhythmia duration under 30 days (median 5 days, range 2-26). Atrial fibrillatory rate (AFR) was estimated using a frequency power spectrum analysis of QRST-cancelled ECG. At 1-month follow-up, 56% of the patients had relapsed to AF. The pre-cardioversion mean AFR of those patients was 399+/-52 fibrillations per minute (fpm) compared with 363+/-63 fpm among patients maintaining SR (P<0.0001). In patients with short AF duration, the difference was even more pronounced (424+/-52 vs. 345+/-65 fpm, P<0.01). In this group, a finding of an AFR above the mean value of the study population predicted AF relapse with high accuracy. CONCLUSION: In patients undergoing cardioversion of persistent AF, AF relapse is predicted by a higher AFR. A stronger association is seen in patients with short arrhythmia duration, reflecting either rapid remodelling or pre-existing changes in those who relapse to AF.