Study limitations
The present case series has several limitations. First, the sample size
is relatively small. This is partly due to our diagnostic criteria of a
macroreentry, based on a minimum of three different sites with short
PPI. Another reason is the retrospective nature of the work, leading to
the exclusion of some cases with incomplete maps. Together, these two
points may result in an underestimation of pseudo-focal ATs prevalence.
Second, smaller circuits confined to one atrial wall may also involve an
epicardial bypass and share some characteristics of our series. However,
their diversity implies a less systematic ablation strategy than that we
report for a macroreentry. Third, the detailed course of the epicardial
bypass was not directly mapped via subxiphoid access. Since the distance
from the breakthrough to the collision site is a surrogate for the
bypass length, the measured velocity was an estimation only.