Incidence of laboratory-defined severe intravascular haemolysis across commercially available pulsed field ablation technologies for atrial fibrillation

Abstract Aims Renal failure due to intravascular haemolysis (IH) has been reported after pulsed field ablation (PFA) of atrial fibrillation (AF). However, IH incidence using the accepted laboratory criteria is unknown. Methods and results In this prospective observational study (Sept 2024–May 2025), consecutive patients undergoing PFA for AF with pentaspline (PS), circular array (CA), or lattice tip (LT) catheters were included. Pre- and post-procedural labs and haemolysis biomarkers were collected. Significant IH was defined as post-procedure free plasma haemoglobin > 100 mg/dL per haematology criteria. Logistic regression (pooled and stratified) was used to identify IH predictors. Among 245 patients (66.9 ± 10.6 years; 68.2% male; 48.2% persistent), PFA was performed using the LT (62), PS (108), or CA (75) catheters. There was a significant difference in the incidence of IH across technologies (37.0%, 26.1%, and 14.7% for PS, CA, and LT, P = 0.002). No demographic or clinical parameters were associated with higher IH risk, while the use of PS was the only independent predictor [odds ratio (OR) 3.42, P = 0.001] of IH. The number of PF lesions increased risk for IH only within the PS group (OR 1.03, P = 0.049). Routine post-ablation laboratories had poor sensitivity/specificity to define severe IH. Conclusion Although over 17% of the cohort met the haematologic definition for significant IH, the absence of clinically significant renal impairment suggests that this threshold may not accurately reflect clinically meaningful haemolysis following PFA. The absence of clinical predictors or laboratory surrogates suggests that the rare risk of renal injury must be balanced with the well-established benefits of PFA when lesions are delivered in moderation optimizing tissue contact.