Defibrillation-guided radiofrequency ablation of atrial fibrillation secondary to an atrial focus

OBJECTIVE Our aim was to evaluate a potential focal source of atrial fibril lation (AF) by unmasking spontaneous early reinitiation of AF after transve nous atrial defibrillation (TADF), and to describe a method of using repeat ed TADF to map and ablate the focus. BACKGROUND Atrial fibrillation may develop secondary to a rapidly dischargi ng atrial focus that the atria cannot follow synchronously with suppression of the focus once AF establishes. Focus mapping and radiofrequency (RF) ab lation may be curative but is limited if the patient is in AF or if the foc us is quiescent. Early reinitiation of AF has been observed following defib rillation, which might have a focal mechanism. METHODS We performed TADF in patients with drug-refractory lone AF using el ectrodes in the right atrium (RA) and the coronary sinus. When reproducible early reinitiation of AF within 2 min after TADF was observed that exhibit ed a potential focal mechanism, both mapping and RF ablation were performed to suppress AF reinitiation. Clinical and ambulatory ECG monitoring was us ed to assess AF recurrence. RESULTS A total of 44 lone AF patients (40 men, 4 women; 32 persistent, 12 paroxysmal AF) with a mean age of 58 +/- 13 years underwent TADF. Sixteen p atients had early reinitiation of AF after TADF, nine (20%; 5 paroxysmal) e xhibited a pattern of focal reinitiation. Earliest atrial activation was ma pped to the right superior(n = 4) and the left superior (n = 3) pulmonary v ein, just inside the orifice, in the seven patients who underwent further s tudy. At the onset of AF reinitiation, the site of earliest activation was 86 +/- 38 ms ahead of the RA reference electrogram. The atrial activities f rom this site were fragmented and exhibited progressive cycle-length shorte ning with decremental conduction to the rest of the atrium until AF reiniti ated. Radiofrequency ablation at the earliest activation site resulted in s uppression of AF reinitiation despite pace-inducibility. Improved clinical outcome was observed over 8 +/- 4 months' follow-up. CONCLUSIONS Transvenous atrial defibrillation can help to unmask, map, and ablate a potential atrial focus in patients with paroxysmal and persistent AF. A consistent atrial focus is the cause of early reinitiation of AF in 2 0% of patients with lone AF, and these patients may benefit from this techn ique, (C) 1999 by the American College of Cardiology.