Variability in Tissue Interface Temperature During Pulse Field Atrial Ablation: Implications for Real-Time Contact Assessment

BACKGROUND: Pulsed field ablation (PFA) can generate low-intensity catheter-tissue interface heating. Recently, a large-focal PFA catheter able to measure the tip-tissue interface temperature has become available. Accordingly, we aimed to characterize the electrode tip-tissue interface temperature dynamics during PFA. METHODS: A retrospective single-center study evaluated PFA lesions in 41 consecutive patients undergoing atrial fibrillation ablation using the lattice-tip catheter. Lesions were grouped by anatomic location with interface temperatures measured via catheter tip thermocouples. The association of predictors with lesion temperatures was evaluated with a mixed-effects model. An analysis of lesion dimensions and interface temperatures was also performed in swine. RESULTS: Among 41 patients, 2779 pulse field lesions were analyzed. Mean peak temperature was 41.7±2.2 °C (range, 37.2 °C–52.8 °C) and average temperature was 39.5±1.4 °C (range, 36.4 °C–46.9 °C). Temperatures exceeded 50 °C in 10 of 2779 (0.4%) lesions, most often in the anterosuperior left superior pulmonary vein (5/10). Univariate analysis showed peak temperature was positively associated with previous lesion temperature ( r =0.65 [95% CI, 0.63–0.67]; P <0.001) and had weak associations with time between lesions ( r =−0.15 [−0.19 to −0.11]; P <0.001) and percentage impedance drop ( r =0.20 [95% CI, 0.16–0.23]; P <0.001). Even after multivariable analysis, the peak temperature remained significantly lowest at the right carina (39.7 °C), anterosuperior right superior pulmonary vein (40.9 °C), and right superior pulmonary vein roof (40.5 °C) locations. Swine demonstrated a moderately strong association between lesion depth with peak temperature ( R =0.53 [95% CI, 0.20–0.75]; P =0.003) and average temperature ( R =0.49 [95% CI, 0.16–0.73]; P =0.007). CONCLUSIONS: Lattice-tip temperatures during PFA vary substantially, with right superior pulmonary vein sites often demonstrating a blunted temperature response compared with other sites. Peak and average temperatures correlated with lesion depth.