A Comparison of the Efficacy of Voltage-directed Cavotricuspid Isthmus Ablation Using Mini Versus Conventional Electrodes

Cavotricuspid isthmus (CTI) ablation is a current first-line management method for typical atrial flutter. A voltage-directed technique that systematically targets points of maximal voltage has be found to reduce procedure and fluoroscopy times without increasing recurrence. We hypothesized that this technique's efficiency would be enhanced by using signals from radial minielectrodes of a novel catheter (IntellaTip MiFi™; Boston Scientific, Natick, MA, USA). Prospectively, atrial flutter patients underwent voltage-directed ablation with a nonirrigated 8-mm-tip catheter. Ablation was either directed by conventional bipolar electrodes (group A, n = 13) or mini-electrodes (group B, n = 17) with the goal of achieving bidirectional block at the CTI and a subsequent observation time of 30 minutes. Total radiofrequency application time and lesion numbers were not significantly different. Group B had a lower mean power [38.7 watts (W) ± 2.0 W versus 44.8 W ± 1.9 W; p < 0.05] and a tendency for longer fluoroscopy and procedure times. In three of the cases in group B, a switch to an irrigated catheter was required in order to achieve bidirectional block. In group A, bidirectional block was obtained in all patients using the nonirrigated catheter with no significant increase in reconnection. Differences in the catheter performance between the two groups were driven by poorer performance of the MiFi™ catheter (Boston Scientific, Natick, MA, USA) in patients presenting in atrial flutter. Electroanatomical mapping revealed a more proximal localization of the maximal voltage by the minielectrodes as compared with the conventional bipolar electrodes, resulting in less efficient identification and ablation of the conducting muscle bundles. Final results indicated CTI ablation using minielectrodes is not superior to conventional bipolar electrodes in the use of 8-mm, nonirrigated electrodes.