Posterior Wall Ablation Characteristics and Esophageal Safety of an Optimized Protocol for Voltage‐Guided, High‐Power Short‐Duration Ablation of Atrial Fibrillation

INTRODUCTION: The ablation index (AI) standardizes lesions in radiofreqency ablation (RF) of atrial fibrillation (AF). High-power, short-duration ablation (HPSD) shortens procedures, but AI is histologically unvalidated in HPSD. We evaluated esophageal safety with voltage-adapted AF ablation using an optimized, AI-guided HPSD (AI-HPSD) protocol. METHODS: Consecutive AF patients undergoing AI-HPSD at 50 W (AI = 400-450 for posterior left atrium (LA); AI ≥ 500 anteriorly) were compared with a recent AF cohort treated by AI-guided low-power, long-duration ablation (AI-LPLD). Esophageal endoscopy was performed 1-3 days postablation. Posterior wall lesion characteristics and endoscopically-detected esophageal lesions (EDEL) were compared. RESULTS: AI-LPLD (n = 100) and AI-HPSD (n = 100) groups had similar baselines, except AI-LPLD had slightly larger LA-area. VISITAG numbers were comparable, but total posterior wall RF time was shorter with AI-HPSD versus AI-LPLD [4.1 (2.1-12.7) vs. 10.9 (5.1-26.6), p < 0.001]. Mean AI and mean impedance drop were higher in AI-HPSD [449 (394-487) vs. 399 (329-485), p < 0.001 and 8.7 (3.9-15.7) vs. 7.4 (3.6-18.2), p = 0.004]. AI standard deviation was lower with AI-HPSD [25 (9-79) vs. 48 (19-100), p < 0.001]. Although Max AI values were higher in AI-HPSD [514 (435-662) vs. 492 (404-644), p = 0.003), maximum impedance drop did not differ significantly. EDEL rate was comparably low at 2% (AI-HPSD) and 4% (AI-LPLD), but AI > 520 occurred more with AI-HPSD (3.5 ± 5.5% vs. 2.5 ± 5.2%; p = 0.048). CONCLUSION: Optimized AI-HPSD at 50 W with posterior LA target AI = 400-450 was not associated with more EDEL. However, a signal for more unacceptable Max AI values existed. We recommend limiting AI to 400 and developing an automatic, AI-guided ablation stop.