Procedural Results
Procedural characteristics and outcomes are provided in Table 2 .
Of the 307 patients treated with amiodarone, 228 (74.3%) underwent CDV during the pre-ablation period as part of a rhythm-control strategy. This included 105 of the 124 amio-failure patients (84.5%) and 123 of the 183 amio-success patients (67.2%). The average time from CDV to subsequent ablation was the same (3months) in the amio-failure and amio-success groups.
Patients underwent either RF (n=251; 81.8%) or cryoballoon (n=55; 18.2%) ablation. There was no difference in ablation modality used between the amio-success and amio-failure patients. Of the 307 patients, 218 (74.3%) underwent index catheter ablation. Patients in the amio-failure group presented either in AF (n=97; 78.2%) or in atrial flutter (n=27; 21.8%). PVI-only was the dominant ablation strategy, performed in 199/307(64.8%) patients. Extra-PVI ablation sites were targeted in 108/307 patients (35.1%) and included roof line lesion sets (26/307) and focal targets (10/307). Extra-PVI ablation was performed in 52 of the 183 amio-success cohort (28.4%) and 56 of the 124 amio-failure cohort (45.1%)
All 307 patients were followed for at least 12 months to survey for arrhythmia recurrence after a 3m blanking period. AAD therapy was discontinued in all patients during the blanking period. Off-drug arrhythmia-free survival rates in the amio-success and amio-failure cohorts were calculated using Kaplan-Meier survival curves (Figure 2 ). The overall 1-year success rate was 57.7% and was not different in the amio-success cohort (55.7%) versus the amio-failure cohort (60.5%; p=0.54). Recurrent arrhythmias included recurrent AF (30.3%), atrial flutter (9.1%), focal atrial tachycardia (0.3%), or a combination of AF and flutter (2.6%) and did not differ between amio-success and amio-failure cohorts.
Ablation success rates in the patients treated for PAF were similar in the amio-success and amio-failure cohorts (55.2 versus 66.0%; p=0.27;Figure 3A ). Similarly, patients with persAF had similar ablation outcomes between the two cohorts, with freedom from AF in 56.3% and 56.8% of patients in the amio-success and amio-failure groups (p=0.91; Figure 3B ).
Complications occurred in 9 of the 307 patients studied (2.9%) and included vascular access site issues (0.7%), aspiration pneumonia (0.3%), pulmonary embolism (0.3%), and cardiac tamponade (1.6%) (Table 3 ). There was no difference in complication rates between the amio-success and amio-failure cohorts.