6. Study limitations
Several limitations of the present study warrant mention. First, data
analyses were not performed at independent facilities blinded to patient
characteristics, which may have resulted in bias in mapping-data
collection. In particular, mean regional voltage was obtained using
arbitrarily selected mapping points within the region, possibly
resulting in biased values. 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,
ablation strategies were at the discretion of attending physician,
possibly affecting rhythm outcomes. Fourth, AF recurrence after
discharge was quantified on the basis of intermittent ECG monitoring,
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.