Introduction

Electrophysiological mechanisms of atrial fibrillation (AF) remain unclear. Localized rotors and focal sources have been identified as potential mechanisms that may represent novel targets for patient tailored ablation beyond pulmonary vein isolation (PVI). AF propagation mapping with high density mapping during repeat ablation procedures has not been studied yet.

Aims

The present study aims at identification of focal sources and constant rotational activity during high density AF propagation mapping using a novel mapping algorithm in patients undergoing repeat ablation of AF after initial PVI.

Methods

Propagation mapping of focal and constant rotational activity was performed in thirty-six consecutive patients undergoing repeat ablation for AF. AF propagation mapping was performed before ablation in all patients. Procedural strategy consisted of assessment of electrical reconduction of the pulmonary veins (PV) as well as re-isolation using radiofrequency ablation. Procedural endpoint was defined as documented entrance and exit block of the PV. In patients with regions of interest (focal/rotational) from propagation mapping, these regions have been targeted by substrate modification. This was also the fact when there was evidence for regional low voltage areas. 

Results

Twenty-seven patients (75%) underwent cryoballoon-based PVI while 6 patients (25%) underwent radiofrequency based PVI before repeat ablation procedure with propagation mapping. In 27 patients (75%) PV reconduction was found during repeat ablation. Mean procedure duration at repeat ablation was 104.9±18.4 minutes, mean fluoroscopy time 5.1±1.6 minutes and mean dosage area product 299.93±219.75 yGym².  Mean duration of propagation mapping in the left atrium was 7.0±3.6 minutes. Total left atrial ablation time was 21.3±5.9 minutes with 4.9± 3.4 minutes of ablation for rotational activity. Mean percentage of low voltage areas was 17.75±4.1%. The majority of patients (66.7%) was classified as I° fibrosis while 16.7% were classified as III° or IV° fibrosis. Mean left atrial diameter was 42±7.3 mm. 

A mean of 142.5±103.4 left atrial focal or constant rotational activities were found per patient. Presence of focal rotational and constant rotational activity before ablation was assessed regarding specific left atrial compartments (Table 1). The most common location for the presence of focal activity were the superior and lateral LA (in 75 and 58% of patients, respectively). Focal and constant rotational activities inside the PVs were rarely identified even in patients with PV electrical reconduction (Table 1).

Conclusion

Propagation mapping using high density mapping catheters is feasible during repeat AF ablation procedures. Focal and constant rotational activity could be demonstrated in all patients. Rotational activity map might be an additional mapping and ablation target in patients undergoing repeat ablation for AF. Further studies are needed to evaluate the clinical impact.

Table 1: