Prevalence and significance of focal sources of atrial arrhythmia in patients undergoing cardioversion of persistent atrial fibrillation

Introduction: Recent reports have highlighted the importance of focal atria l arthythmias as a curable cause for a group of patients with frequently re current paroxysmal atrial fibrillation (AF). The importance of this arrhyth mia mechanism in the general population of patients with persistent AF is u nknown. Methods and Results: After successful internal cardioversion of 50 consecut ive patients with persistent AF (mean age 60 years, mean duration of AF 26 months), endocardial activity in the immediate posteardioversion period was analyzed for the presence of focal atrial activity, Postcardioversion atri al arrhythmias were considered to be focal if there was evidence of a local ized source of repetitive early atrial activation, either in the form of ii ) self-terminating monomorphic atrial tachycardia (at least five beats) or (2) recurrences of AF with an initial atrial activation sequence (first fiv e beats) that was both monomorphic and reproducible with repeated recurrenc es, Evidence for a focal atrial arrhythmia was present in 20 of the total g roup of 50 patients (40 %). Multivariate analysis of clinical characteristi cs revealed the diagnosis of lone AF as the only independent predictor of a focal source of AF (P = 0.028), Thirty-nine patients were discharged from hospital in sinus rhythm, At 1-month follow-up, 25 (64%) of these 39 patien ts had suffered AF recurrence. The only significant predictor of AF recurre nce was evidence of a focal source of atrial arrhythmia immediately after c ardioversion, with a relative risk of 1.73 (range 1.1 to 2.7; P = 0.015). Conclusion: Focal atrial arrhythmias are common in patients presenting with "idiopathic" persistent AF, suggesting a possible causative role in the ge neration of this common arrhythmia.