Arrhythmia Recurrence After Amiodarone Post AF Ablation
As we did not perform continuous ECG monitoring but only performed planned 12 lead ECGs, 3-day Holter-monitorings, and otherwise symptom-driven cardiac rhythm monitoring, we could have missed some asymptomatic recurrences. The ablation technique was not completely uniform between the two ablation centres but since patients were stratified according to centre when randomized, it is unlikely that this would have influenced the findings between the two treatment groups. In addition, this might be more representative for every-day life in larger specialized clinics where different ablations techniques are used.
The power calculation and sample size were based on a 50% reduction of recurrence rate. Hence, a lower reduction of recurrence rate at 6 months might not be detected in this study. This decision was made with the potential side effects of amiodarone in mind.
Only 16% of the referred patients were randomized in the trial, which makes it a rather selected population. A follow-up of 6 months is relatively short and one could also argue that since amiodarone has long half-life, a lingering antiarrhythmic effect could persist beyond the blanking period and reduce recurrence at 6 months in the amiodarone group; however, since we found no statistically significant difference in recurrence at 6 months, it is unlikely that this would be any different at the 12-month follow-up.
Subgroup analyses of the primary end-point based on the type of AF (paroxysmal/persistent) and whether patients were treated with PVI only or PVI plus additional ablations might have been interesting. The latter comparison might even more accurately reflect the extent of electroanatomical remodelling of the left atria, thus provide better information on mechanisms and possible treatment success of the ablation than the clinical term paroxysmal/persistent. However, in the present setting, such subgroup analysis would be statistically underpowered and were not performed due to the risk of false-negative findings.
Limitations
As we did not perform continuous ECG monitoring but only performed planned 12 lead ECGs, 3-day Holter-monitorings, and otherwise symptom-driven cardiac rhythm monitoring, we could have missed some asymptomatic recurrences. The ablation technique was not completely uniform between the two ablation centres but since patients were stratified according to centre when randomized, it is unlikely that this would have influenced the findings between the two treatment groups. In addition, this might be more representative for every-day life in larger specialized clinics where different ablations techniques are used.
The power calculation and sample size were based on a 50% reduction of recurrence rate. Hence, a lower reduction of recurrence rate at 6 months might not be detected in this study. This decision was made with the potential side effects of amiodarone in mind.
Only 16% of the referred patients were randomized in the trial, which makes it a rather selected population. A follow-up of 6 months is relatively short and one could also argue that since amiodarone has long half-life, a lingering antiarrhythmic effect could persist beyond the blanking period and reduce recurrence at 6 months in the amiodarone group; however, since we found no statistically significant difference in recurrence at 6 months, it is unlikely that this would be any different at the 12-month follow-up.
Subgroup analyses of the primary end-point based on the type of AF (paroxysmal/persistent) and whether patients were treated with PVI only or PVI plus additional ablations might have been interesting. The latter comparison might even more accurately reflect the extent of electroanatomical remodelling of the left atria, thus provide better information on mechanisms and possible treatment success of the ablation than the clinical term paroxysmal/persistent. However, in the present setting, such subgroup analysis would be statistically underpowered and were not performed due to the risk of false-negative findings.
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