Development and validation of an algorithm to predict the success of the ablation of macroreentrant atrial tachycardia.

Ablation of macroreentrant atrial tachycardia (MRAT) is challenging because of complex anatomy and multiple reentrant loops. In order to define an effective ablation strategy, 3-dimensional electroanatomic mapping proved very useful. To identify predictors of ablation procedure failure may be helpful for patients treatment. In the first part of our study we analyzed into details the electroanatomical features of the reentry circuit in MRAT and we compared the characteristics of successfully versus unsuccessfully consecutive treated patients undegoing electroanatomic mapping and ablation of MRAT in order to identify variables predicting the ablation outcome. 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. We demonstrated a significant difference as to the electroanatomic mapping characteristics: successfully treated cases showed a narrower target isthmus with a slower conduction velocity across the isthmus itself. In the second part of our research, we analyzed the relation between the strongest predictors of procedure outcome identified in part I (MDI width and conduction velocity across the MDI) and the chance of success of the ablation procedure. In order to analyze this relation and to predict the difficulty of the ablation procedure, we developed an algorithm and we validated prospectively the accuracy of the developed model in a second patient series.