Char Formation During Very High-Power Short-Duration Ablation for Atrial Fibrillation

Pulmonary vein (PV) isolation using very high-power short-duration (vHPSD) radiofrequency catheter ablation is an effective treatment strategy for atrial fibrillation. However, PV isolation using vHPSD ablation (vHPSD-PVI) carries a potential risk of char formation. We aimed to assess the incidence, patient characteristics, and procedural factors of char formation during vHPSD-PVI.

Fifty consecutive patients scheduled to undergo initial PV isolation (PVI) were prospectively included. PVI was performed using a QDOT MICRO^TM catheter in the vHPSD setting (90 W/4 s). PVs were divided into eight segments, and char formation around the ablation catheter was evaluated after the ablation of each segment. Patient characteristics and procedural parameters were analyzed to determine the risk factors for char formation. During vHPSD-PVI, char formation was observed in 24 (48.0%) patients, primarily at the groove between the tip and ring electrodes. Among the segments, the incidence of char formation was the highest (26.0%) in the anterior and posterior right inferior PV (RIPV) segments (p < 0.001). One patient with char formation developed symptomatic thromboembolism after the procedure. The left atrial volume index (LAVI) (odds ratio [OR], 1.089; 95% confidence interval [CI], 1.011-1.173; p = 0.024) and parallel catheter orientation (OR, 1.592; 95% CI, 1.416-1.791; p < 0.001) were independent predictors of char formation.

Char formation occurred in 48.0% of the patients during vHPSD-PVI. Application to the RIPV segment, a higher LAVI, and parallel catheter orientation were associated with an increased risk of char formation, indicating that vHPSD applications should be avoided under these conditions.