Catheter Ablation Versus Antiarrhythmic Medication As First Line Therapy in Paroxysmal Atrial Fibrillation: on Treatment Analysis of the Mantra-Paf Data

Background: MANTRA-PAF is a large randomized multicenter trial comparing radiofrequency catheter ablation (RFA) and antiarrhythmic drug (AAD) therapy as first line treatment of paroxysmal atrial fibrillation (PAF). Intention-to-treat analysis showed no significant difference in cumulative AF burden, but at 24 months AF burden was significantly lower in the RFA than in the AAD group. In the present on-treatment analysis we compared three groups of patients: those who received only the prescribed treatment (pure RFA and pure AAD groups) and those treated with combination of RFA and AAD (cross-over group). Methods: A total of 294 AAD naïve patients with PAF were randomly assigned to RFA (146 patients) or class IC/III AAD therapy (148 patients). Cumulative and per-visit AF burden (i.e., percentage of time in AF) was evaluated from 7-day Holter recordings at baseline and after 3, 6, 12, 18, and 24 months. The patients were considered free from AF if no AF episodes longer than 60 s were detected. In the AAD group, 54 patients (36%) underwent supplementary ablation and in the RFA group 30 patients (21%) received antiarrhythmic medication after the 3 months blanking period (at 24 months 9% were on AAD). Eight patients were excluded from the analysis because they did not receive the index treatment. Results: At 24 months, AF burden was significantly lower in the pure RFA group (n=110) than in the pure AAD (n=92) and the cross-over (n=84) groups (90th percentile 1% vs. 10% vs. 19%, P=0.007), and more patients in the RFA than in the other groups were free from any AF (89% vs. 73% vs. 74%, P =0.006). The cumulative AF burden was significantly lower in the pure RFA and AAD groups than in the cross-over group (90th percentile 10% vs. 6% vs. 24%, P<0.001). During the 2 year follow-up period 63%, 59% and 21% (P<0.001) of the patients in the pure RFA, pure AAD and the cross-over group had no AF episodes in any Holter recording, respectively. There was no significant difference in the number of severe complications between the groups. Conclusions: These data indicate that RFA is superior to AAD as first line treatment in a large subset of patients with highly symptomatic PAF. The results are pertinent among relatively young and healthy subjects and should not be extrapolated to elderly patients or to those with comorbidities.