2.5 Real-Time Phase Mapping
After the integration of the
anatomical 3D models of the LA and PVs obtained from the MRI, mapping
was performed using the NavX system (Abbott, Chicago, IL) as a guide. A
20-pole circular mapping catheter (OptimaTM or
Reflexion HDTM, Abbott) and ablation
catheter-reconstructed LA posterior anatomy was aligned with the
MRI.13 To detect the distribution of the AF drivers,
an online real-time phase mapping system (ExTRa Mapping) was used. The
detail of this mapping system was previously described.7 ExTRa Mapping was applied to persistent AF patients
and as a result, each wave dynamics were classified into 3 patterns,
meandering rotors (MRs), multiple wavelets (MWs), and planar wave.
Planar wave propagation was defined as passive activation, whereas MR
and MW were defined as non-passive activations. Furthermore,
non-passively activated areas (NPAs), a region where
non-passive activations were
frequently observed, were
automatically detected according to the value of the “non-passively
activated ratio (%NP)” (the ratio of the form of MRs and/or MWs
assumed to contain AF drivers to the recording time).5NPAs were determined as areas up to the top 7 highest %NP values
greater than 50%. Thus, the NPAs could be considered as the area where
AF drivers could be frequently found. To evaluate the distribution of
the NPAs, the region of the whole LA was divided into the following 8
segments: PV antrum, roof, anterior, posterior, lateral, bottom, septum,
and left atrial appendage (LAA) base segments. Moreover, we evaluated
the proportion of MRs and MWs in the %NP within the NPAs in the lesser
and heterogenous LGE areas.