Evaluation of a Novel High-Resolution Mapping Technology for Ablation of Recurrent Scar-Related Atrial Tachycardias

Background RhythmiaTM is a new technology capable of rapid and high-resolution mapping. However, its potential advantage over existing technologies in mapping complex scar-related atrial tachycardias (AT) has not been yet evaluated. Objective To examine its utility for mapping scar-related AT in patients who had failed previous ablation procedure(s). Methods This multicenter study included 20 patients with recurrent AT within 2 years after a previous ablation procedure (1.8±0.7 per patient). In all cases, the AT could not be adequately mapped during the index procedure due to scar with fractionated electrograms precluding accurate time annotation, frequent change in the tachycardia in response to pacing, and/or degeneration into atrial fibrillation (AF). These patients underwent repeat mapping and ablation procedure with RhythmiaTM. Results From a total of 28 inducible ATs, 24 were successfully mapped. Eighteen ATs (75%) terminated during radiofrequency ablation and 4 (16.6%) with catheter pressure or entrainment from the site of origin or isthmus. Two ATs that were mapped to the interatrial septum slowed but did not terminate with ablation. In 21/24 ATs the mechanism was macroreentry, while in 3/24 the mechanism was focal. Interestingly, in 5 patients with previously failed ablation of an allegedly “focal” tachycardia, high-resolution mapping demonstrated macroreentrant arrhythmia. The mean mapping time was 28.6±17 minutes and the mean radiofrequency ablation time to arrhythmia termination was 3.2±2.6 minutes. During a mean follow-up of 7.5±3.1 months, 15 (75%) of 20 patients were free of AT recurrences. Conclusion The RhythmiaTM mapping system may be advantageous for mapping complex scar-related AT.