We were pleased to read the Letter to the Editor about our series on cryoballoon ablation (CA) for atrial fibrillation (AF) at a low-volume hospital.1 In the current economic crisis, health managers are debating the advisability of pooling resources and restricting diagnostic or therapeutic procedures (including complex ablations) to centers of excellence. An additional factor in this debate is the fact that 80% of arrhythmia units perform fewer than 50 ablations for AF annually; but how do their results compare to the success rates of high-volume centers?

We selected candidates without heart disease and with highly symptomatic and refractory AF because they would be most likely to show a clinical and electrophysiological response to ablation. In our opinion, the good results for acute efficacy observed in our series are more related to these very strict selection criteria than to any incorrect assessment of pulmonary vein isolation or incomplete follow-up, which included 24-hour Holter monitoring 4 times during the first year. Following current consensus, we defined relapse as documented AF episodes lasting more than 30seconds. We also agree that an implantable Holter monitor is useful to detect clinically silent AF episodes, which are often underdiagnosed.2 However, our main goal in AF ablation is simply to provide symptomatic relief and discontinue antiarrhythmic agents.

Our series does not prove that the learning curve is less steep for CA than radiofrequency ablation, although our findings appear to suggest this. At high-volume hospitals, there is no difference because the cardiologists are already highly experienced in radiofrequency ablations, and can actually perform them faster than CA techniques.3

Post-CA electroanatomic mapping confirms the formation of dense, confluent scarring, which is electrically silent, on 40% of the left atrial surface, particularly on the posterior wall.4 This helps to minimize the formation of conduction blocks, which cause AF relapse. In our series, post-CA reablation procedures (performed with radiofrequency) confirmed the presence of two conduction blocks in most cases, which simplifies the reablation procedure (unpublished data).

In terms of complications, our safety results were positive, and comparable with the findings of other series. We do not feel they were “negligible”. It is certainly not our intention to discuss whether serious complications (including death) are acceptable when treating theoretically nonserious arrhythmias in healthy patients without heart disease.