Intraprocedural use of ibutilide to organize and guide ablation of complex fractionated atrial electrograms: preliminary assessment of a modified step-wise approach to ablation of persistent atrial fibrillation.

INTRODUCTION: While able to achieve clinical success, the current step-wise approach to persistent atrial fibrillation (AF) ablation requires considerable "substrate" ablation and frequently mandates multiple procedures to address consequent atrial tachycardias (ATs). An alternative strategy minimizing the amount of ablation while maintaining clinical success would be desirable. We hypothesize that intraprocedural administration of a low-dose antiarrhythmic drug (AAD) during AF will organize areas of passive activation and not affect areas critical to AF maintenance, thereby potentially minimizing the ablation lesion set.

METHODS AND RESULTS: Eleven patients (age = 55 +/- 6 years; LA = 48 +/- 15 mm; median AF duration = 3 years) with persistent AF undergoing catheter ablation were enrolled in this exploratory prospective observational study. After pulmonary vein (PV) isolation, a mean cycle length (mCL) map was created and areas with mCL <120 ms were considered to represent complex fractionated atrial electrograms (CFAE). Ibutilide (0.25-1.0 mg) was then administered and a second mCL map created. Ablation lesions were placed at CAFE sites identified after ibutilide administration. Activation and/or entrainment mapping was employed to address ATs. The endpoint of ablation was achieving sinus rhythm. The average LA mCL increased (146 vs 165 ms, P = 0.01) and the LA CFAE surface area decreased after ibutilide administration. Additional ablation organized AF to either sinus rhythm or AT in 10/11 (91%) patients. After a median follow up of 455 days, 8 of 11 (72%) patients were free from AF. Three patients underwent a repeat ablation procedure (average 1.27 ablations/patient).

CONCLUSIONS: Ibutilide administration may organize atrial activity and facilitate AF termination during ablation while minimizing the ablation lesion set.