6. Limitations
Several limitations of the present study warrant mention. First, LACV measurement was done by a single medical engineer, possibly resulting in biased data, albeit that inter-observer variability was 0.025 m/s, which we assume to be sufficiently low. Second, the study did not investigate data from repeat procedures, and did not examine the reconnection rate of isolated pulmonary vein. Accordingly, AF recurrence does not necessarily mean that the patient had an extra-pulmonary-vein AF substrate. Third, we did not perform right atrial mapping, although the right atrium is also thought to play a role in AF development, in some patients at least. Fourth, AF recurrence after discharge was quantified on the basis of intermittent short-time ECG and symptom-triggered ECG, giving rise to the possibility that asymptomatic episodes of AF might have been missed. Finally, the study was conducted under a single center, observational design. Confirmation awaits a prospective multicenter study.