Electroanatomic Mapping and Ablation of Macroreentrant Atrial Tachycardia: Comparison Between Successfully and Unsuccessfully Treated Cases

Ablation of Macroreentrant Atrial Tachycardia. Introduction: Ablation of macroreentrant atrial tachycardia (MRAT) is demanding and identification of predictors of failure may be of help in patient management. This study compares the characteristics of successfully versus unsuccessfully treated patients undergoing electroanatomic mapping (EAM) and ablation of MRAT. Methods and Results: Consecutive patients undergoing EAM and ablation of MRAT were included. Ablation was linearly placed at the mid‐diastolic isthmus (MDI) to achieve arrhythmia interruption and conduction block. Variables were analyzed for predictors of both procedural failure and cumulative failure (procedural failure + early recurrences). Fifty‐two patients (37 M; age 64 ± 16 years) with 56 MRATs were considered. The MRAT was in the right atrium in 25 morphologies (45%) and 32 (57%) showed a double‐loop reentry. Fifty‐one morphologies (91%) in 47 patients were successfully treated; 3 patients had early recurrences of the same MRAT. None of the clinical variables considered significantly differed in the successfully treated group as compared to the unsuccessfully treated. Conversely, there was a significant difference as to the EAM characteristics: successfully treated cases showed a narrower target isthmus with a lower voltage amplitude and slower conduction velocity (CV). In the MDI, a CV >60 cm/sec and a width >40 mm were the strongest predictors of procedural failure and cumulative failure, respectively. Conclusions: In this patient population, while the clinical variables did not differ significantly, there was a significant difference in the EAM characteristics between successfully and unsuccessfully treated cases. CV and width of the isthmus target for ablation were the strongest independent predictors of procedure outcome. (J Cardiovasc Electrophysiol, Vol. 21, pp. 155‐162, February 2010)