High energy transcatheter cardioversion of chronic atrial fibrillation.

A new technique of internal transcatheter cardioversion of chronic atrial fibrillation using high energy shocks (200 to 300 joules) was performed in 10 patients. In all patients, external cardioversion (300 to 400 joules) and pharmacologic therapy failed to restore sinus rhythm. Atrial fibrillation was poorly tolerated despite digitalis therapy alone (five patients) or in combination with amiodarone (five patients). High energy transcatheter cardioversion was performed by pulling back the atrioventricular (AV) junction catheter just inferior to the site of His bundle recording and delivering the shock between a proximal electrode (catheter) and backplate (anode). High energy internal cardioversion restored sinus rhythm in 9 of the 10 patients. However, atrial fibrillation recurred within 3 min in two of them; in the remaining patient, the procedure failed to terminate atrial fibrillation. The only complication observed was transient (3 to 315 s) heart block immediately after shock delivery and this was treated by temporary pacing. Seven patients had sinus rhythm on discharge from the hospital, but in three, recurrent atrial fibrillation appeared at 8 days and 2 and 4 months, respectively. A second attempt of transcatheter cardioversion was performed in two patients and was successful in one patient. With a follow-up ranging from 2 to 11 months, five patients continued to have sinus rhythm. These preliminary results suggest that high energy internal cardioversion may be an alternative to AV junction ablation in selected patients with poorly tolerated chronic atrial fibrillation in whom external cardioversion was unsuccessful.