Successful Treatment of Macroreentrant Atrial Tachycardia by Radiofrequency Ablation Targeting Channels with Continuous Activation

Background Macroreentrant atrial tachycardia (MRAT) is frequently unresponsive to antiarrhythmic drugs. The application of three-dimensional (3D) mapping and entrainment pacing contributes to a high success rate for radiofrequency ablation, but programmed electrical pacing may either terminate or transform clinical tachyarrhythmias. On the basis of clinical experiences of the use of ventricular tachycardia ablation, channels with continuous activation are suitable for reentrant circuits, and ablation at these channels can lead to noninducibility of ventricular tachycardias. We reviewed patients referred for symptomatic MRAT with identified channels with continuous activation and evaluated the efficacy of MRAT ablation by targeting these channels. Methods Fifteen consecutive patients (10 men, 49 ± 14 years) with MRAT illustrated by endocardial activation maps using a 3D electroanatomical mapping system (CARTO™, Biosense Webster, Diamond Bar, CA, USA) were included in this study. Continuous activation was defined as double or continuous potentials without an isoelectric interval, and sites with continuous activation were tagged for measurements of channel properties. Radiofrequency ablation was performed at those targeted sites located within the reentrant circuit. Results Radiofrequency ablation successfully eliminated MRAT in all patients. The mean cycle length was 283 ± 60 ms, and the longest activation duration was 112 ± 38 ms. The minimal and maximal bipolar voltage amplitudes were 0.13 ± 0.1 mV and 0.7 ± 0.6 mV, respectively. The targeted ablation length and width were 28.9 ± 15.3 mm and 9.4 ± 3.3 mm, respectively. Conclusion Radiofrequency ablation of MRAT targeting channels with continuous activation using a 3D electroanatomical mapping system yields a high success rate.