Additional diagnostic value of mini electrodes in an 8-mm tip in cavotricuspid isthmus ablation

Background: Eight-mm ablation catheters are widely used in cavotricuspid isthmus ablation (CTI) for treatment of right sided atrial flutter. However a high success rate, these large ablation tips comes with adisadvantage of lower resolution of fractionated signals. Purpose:The aim of this study was to evaluate the additional diagnostic value of the electrograms recorded from mini electrodes (MEs) in an 8-mm ablation catheter tip during CTI. Methods: CTI-Ablation procedures were compared retrospectively in two groups, namely, group A: The Abbott Safire 8-mm tip with a 3D mapping system (n =37) and group B: The Boston Scientific MiFi IntellaTip XP 8-mm tip without a 3D mapping system (n=13). We analyzed acute procedural success, ablation characteristics and recurrence rate at one-year follow-up. Electrograms from MEs were analyzed right before the onset of the critical ablation application that resulted in acute CTI-block. We determined whether these ME electrograms had additional diagnostic value in addition to of the 8-mm tip derivedelectrogram. Results: At the onset of the critical ablation application, the MEs had an important additional value in 3 out of 13 cases as local signals were sensed on the MEs that were not recorded by the 8-mm tip electrode. In 2cases the ME did not show local electrograms although the ablation was still effective. Acute procedural and long-Term success were observed in all patients. No differences were found in time to bidirectional block, procedure time or fluoroscopic exposure. Conclusions: Our data show that signals recorded from the MEs had additional diagnostic value, but only in a small percentage of the patients. We did not observe, although omitting 3D-mapping in the ME group, any difference between groups with regard to procedural or ablation characteristics during CTI-Ablation.