Actual tissue temperature during ablation index‐guided high‐power short‐duration ablation versus standard ablation: Implications in terms of the efficacy and safety of atrial fibrillation ablation

Background Actual in vivo tissue temperatures and the safety profile during high‐power short‐duration (HPSD) ablation of atrial fibrillation have not been clarified. Methods We conducted an animal study in which, after a right thoracotomy, we implanted 6–8 thermocouples epicardially in the superior vena cava, right pulmonary vein, and esophagus close to the inferior vena cava. We recorded tissue temperatures during a 50 W‐HPSD ablation and 30 W‐standard ablation targeting an ablation index (AI) of 400 (5–15 g contact force). Results Maximum tissue temperatures reached with HSPD ablation were significantly higher than that reached with standard ablation (62.7 ± 12.5 vs. 52.7 ± 11.4°C, p = 0.033) and correlated inversely with the distance between the catheter tip and thermocouple, regardless of the power settings (HPSD: r = −0.71; standard: r = −0.64). Achievement of lethal temperatures (≥50°C) was within 7.6 ± 3.6 and 12.1 ± 4.1 s after HPSD and standard ablation, respectively (p = 0.003), and was best predicted at cutoff points of 5.2 and 4.4 mm, respectively. All HPSD ablation lesions were transmural, but 19.2% of the standard ablation lesions were not (p = 0.011). There was no difference between HPSD and standard ablation regarding the esophageal injury rate (30% vs. 33.3%, p > 0.99), with the injury appearing to be related to the short distance from the catheter tip. Conclusions Actual tissue temperatures reached with AI‐guided HPSD ablation appeared to be higher with a greater distance between the catheter tip and target tissue than those with standard ablation. HPSD ablation for