Mapping and ablation efficacy of a lattice-tip catheter with dual ablation properties in the treatment of complex atrial tachycardias

The widespread performance of catheter ablation for atrial fibrillation (AF) has significantly increased the incidence of complex atrial tachycardias (ATs) originating from a diseased or previously ablated myocardial substrate. Under these circumstances, extensive areas of fibrosis or lines of block may complicate the interpretation of activation maps and subsequently the successful diagnosis of the underlying mechanism of the AT. A novel ablation catheter, combining high density mapping and dual ablation properties has been recently released for the treatment of AF. The system has been proven highly effective for both the establishment of the diagnosis and the ablation of a variety of ATs in one of our previous studies.

In the current study we aimed to assess the performance of the novel system in the establishment of the diagnosis and the ablation efficacy in a challenging cohort of patients presented with complex ATs and history of previous catheter ablation.

Patients with documented ATs and history of previous catheter ablation or surgery were included in the study. Cases of cavotricuspid isthmus dependent atrial flutters were excluded. Activation mapping was used for the establishment of AT mechanism. Confirmation with entrainment was performed, whenever appropriate. Accuracy of the activation mapping in diagnosis, acute ablation efficacy (termination of AT during ablation followed by non-inducibility) and procedural characteristics were the study endpoints. Bidirectional block of linear lesions was validated with pacing maneuvers and activation remap.

11 patients were included (6 mitral flutters, 2 roof flutters, 2 focal/microreentry ATs and one macroreentrant AT involving the anterior wall of the left atrium). Proper diagnosis of the tachycardia mechanism was established by the activation map in all cases. In two cases with extensive atrial fibrosis, activation mapping revealed the area of a critical isthmus that led to immediate termination of the AT with one single lesion. Mean mapping time was 8.5±3.1 minutes with acquisition of 380.1±129 mean mapping points/minute. Mean ablation time was 40.2±22.7 seconds. Conversion to sinus rhythm during ablation was achieved in all cases with the exception of a mitral flutter that converted to cavotricuspid isthmus dependent atrial flutter. No major or minor complications occurred.

In a cohort of patients with complex ATs and history of previous catheter ablation, the novel lattice tip catheter that combines high density mapping and dual ablation properties successfully suggested the underlying mechanism of the tachycardia by the pattern of activation in activation maps in all cases. The delivered lesions were highly effective with acute termination of ATs and achievement of bidirectional block in linear lesions.