Left atrial remodelling and functional consequences after pulsed-field ablation: comparison of pulmonary vein isolation alone versus extensive lesion sets

Background Pulsed-field ablation (PFA) is a novel, tissue-selective ablation modality, making it an attractive tool for extensive atrial substrate modification. The impact of extensive PFA on the left atrium (LA) is unknown. Aims We compared LA remodeling after pulmonary vein isolation (PVI-only) versus PVI with additional lesion sets (PVI-plus). Methods Seventy-eight patients (51 PVI-only, 27 PVI-plus; median age 70 years, 64% male) underwent PFA. Echocardiography was performed median 144 days post-ablation to assess LA volume index (LAVi), emptying fraction (LAEF), reservoir and contractile strain (LArS, LActS) and stiffness index (LASI). Plasma soluble suppressor of tumorigenicity-2 receptor (sST2) levels were measured. Arrhythmia recurrence was evaluated at follow-up. Propensity score matching was used to control for baseline differences. Results Despite similar baseline LA volumes, PVI-plus patients had higher LAVi (p=0.017), lower A-wave velocity (p<0.001), lower LAEF (p=0.002), lower LArS (p=0.004) and LActS (p=0.005), and higher LASI (p<0.002) after PFA, and higher sST2 levels (p=0.035). PVI-only was associated with lower LAVi (p=0.003), better strain (LArS p=0.018; LActS p=0.020), lower LASI (p=0.046) and lower sST2 (p=0.009), even after adjustment for relevant clinical factors. No patients developed manifest stiff LA syndrome. However, PVI-plus associated with a higher risk of arrhythmia recurrence (HR=3.03, p=0.041). Impaired LArS (HR=1.15; p<0.001), LActS (HR=1.25, p<0.001) and higher LASI (HR=1.68, p=0.010) predicted arrhythmia recurrence. Conclusion Greater LA remodeling and higher arrhythmia recurrence rates were observed after extensive LA PFA as compared to PVI-only. These findings suggest caution in applying extensive PFA in the LA, and warrant further investigation.