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.