High frequency stimulation for verifying durable lesions during atrial
fibrillation ablation.
Abstract
Introduction Exit block, which is difficult to strictly confirm and
cannot be adopted for adenosine triphosphate (ATP) injections to provoke
dormancy, is an essential concept of atrial fibrillation (AF) ablation.
We investigated exit conduction using high frequency stimulation (HFS)
and evaluated whether dormant “exit” conduction of the pulmonary veins
(PVs) and left atrial posterior wall (LAPW) would remain in patients in
which an encircling isolation of all PVs and LAPW isolation (Box PVI)
were performed. Methods We enrolled 345 consecutive patients with
various severities of AF undergoing a Box PVI and defined the procedure
endpoint as complete bidirectional block with no dormant “entrance and
exit” conduction of all PVs and the LAPW using HFS and ATP. Results
Dormant “exit” conduction of the PVs with HFS delivered at the PV
carina following an ATP injection remained in 0.9% after additional
applications, and that for the LAPW was provoked in 5.5%, which
remained in 1.4%. Our definition of a complete bidirectional Box PVI
was satisfied in 79.7% and showed the best clinical outcome. In the
non-paroxysmal AF group, there were significant differences in the
recurrence rates between the groups with and without a complete LAPW
isolation, however, the clinical outcome was independent of a complete
LAPW isolation in the paroxysmal AF group. Conclusion HFS delivered at
the PV carina and LAPW following a Box PVI could clearly elucidate true
exit block, and a concomitant ATP injection could define dormant
“exit” conduction, suggesting incomplete lesions that had been missed.