4.6 Study limitations
Our study had several limitations. First, the sample size was relatively
small. Second, some patients underwent a prior ablation. In such cases,
we could not completely discriminate between the ablation lesions and
pre-existing atrial fibrosis around the PVs. Furthermore, the LGE site
might have been overestimated on the posterior wall adjacent to the
vertebrae and anterior wall adjacent to the aortic cusp due to wall
compression by those organs. Third, the novel phase mapping system
employed in this study might have include some unknown limitations,
because this system is widely available in Japan, but not in other
countries. We hope this system will spread to the rest of the world in
the future. Fourth, we directly observed the AF wave dynamics in
realātime by applying our novel phase mapping system, but it was still
very difficult to extract the real AF drivers from the various NPAs
detected by this system. Although not all NPAs coincided with true AF
drivers, we strongly believe that most NPAs with high %NP values
contained, more or less, true AF drivers.