Limitations
First, this was a single-center retrospective study with a small number of cases. As the inherent limitation of the retrospective study, the study protocol regarding the ablation and ATP challenge were not consistent among the patients. For instance, one patient did not undergo HFS (Case 1); another patient (Case 6) did not undergo repeat ATP injection at the end of the procedure. Second, HFS was not systematically performed in all the non-PV trigger sites. However, some of the non-PV trigger sites, such as the Marshall tract or distal portion of CS, might not necessarily provoke the vagal response to HFS because of the low sensitivity of HFS and the effect of prior PV/Box isolation on the interaction among the GPs.6, 18Third, we did not include the patients with ATP-induced frequent atrial premature complexes.
Finally, the relationship between the episodes of AF and vagal tone predominance was not thoroughly reviewed. Therefore, further studies are warranted to elucidate the association between ATP-induced AF and vagal AF.