Lesion characteristics after Pulsed-Field Ablation in Patients with Paroxysmal Atrial Fibrillation and a Left Common Ostium (PFALCO RE-MAP STUDY)

Approximately one-fifth of the patients undergoing pulmonary vein isolation (PVI) have a left common ostium (LCO). These patients tend to have a worse arrhythmia-free survival when treated with a single shot device, which might be related to the lesion location and ablation thermodynamics.

This study evaluates lesion characteristics around the LCO in paroxysmal atrial fibrillation (AF) patients treated with a multipolar pulsed-field ablation (PFA) modality.

Twenty-two patients underwent PFA following the manufacturers’ recommendations. When all pulmonary veins (PV) were deemed isolated, a filtered (40 – 300hz) unipolar electro-anatomical map (EAM) was created using the PFA catheter. After the procedure, three experienced operators were asked to draw a fictional ablation line encompassing the LCO in the EAM that was blinded for voltage. Outcome measurements were the average distance from the lesion to the drawn line and the operators’ satisfaction with the lesion characteristics.

The median age was 61 years [56 – 73], 59% were male, and the median CHA₂DS₂-VA was 1.0 [0.0 – 2.0]. The median LCO dimensions were 25.1mm [19.6 – 29.9] (length), 20.1mm [16.0 – 23.4] (anterior-posterior), and 30.5mm [26.0 - 32.8] (superior-inferior). The distance (lesion – fictional ablation line) at the left atrium roof was 3.6mm [-4.8 – 11.2], mid posterior wall 3.3mm [-2.6 – 8.9] and inferior -1.7mm [-7.9 – 2.7]. A negative value represents a too proximal lesion and a positive value a too distal lesion. Based on the EAM, the majority of the operators (≥2/3) considered unintended ablation at the mitral isthmus or posterior wall in 9 patients (40.9%), would perform additional ablation at the LCO in 11 patients (50.0%), and had no remarks on the LCO lesion in 6 patients (27.3%).(Figure) Also, electrical activity in the right superior PV was found in 4 patients (18.2%).

The LCO lesion location after PFA in paroxysmal AF patients varies widely as compared to the fictional ablation line. According to three experienced operators, unintended ablation and electrical activity or a too distal ablation lesion location were present in a substantial group of patients. Whether these findings will influence arrhythmia-free survival has yet to be determined. However, they do emphasize the importance of a critical catheter positioning, a waiting period, and might support the use of a 3D-mapping system in LCO patients.