Mapping the non-PV, non-Box, and non-SVC trigger
In this case series, ATP challenge testing reproducibly provoked AF.
We tried to identify the trigger sites considering the anatomical
distribution of the GP around both atria. We carefully observed the
initial beats at the onset of the induced AF. If we supposed the trigger
PACs should come from GP regions, we proved the presence of GP by
applying high-frequency stimulation (HFS) (20 Hz) at the suspected
trigger region. A positive response was defined as an increase in the
R-R interval by > 50% during AF.6 The
sites with positive responses to HFS were marked on the 3-D mapping
system, and then we applied RF ablation there at the power of 30 to 35
watts for 30 to 60 seconds. Following each RF application, HFS was
repeated at the same site to confirm that the positive response was
eliminated. RF applications were repeated if the positive response to
HFS was still elicited.
When the trigger foci were thought to be not associated with GP regions,
we put the Lasso catheters close to the suspected region and repeated
ATP injection for detailed mapping. We performed additional ablation to
eliminate the foci if it could be identified.
We introduced this “GP-based approach” since Case 2. In Case 1, we
tried to identify the trigger sites, observing the first beats that
initiated AF. CFAE was also targeted to reduce the total number of
electric cardioversion and ATP testing. Finally, we administered ATP at
least twice to verify the noninducibility of AF, if possible.