Acute kidney injury after catheter ablation of atrial fibrillation: Comparison between different energy sources

Pulsed field ablation (PFA) is an innovative technology recently adopted for treating atrial fibrillation (AF). Preclinical and clinical studies have reported a reassuring safety profile because of its tissue-specific effect, sparing adjacent tissues.1Turagam M.K. Neuzil P. Schmidt B. et al.Safety and Effectiveness of Pulsed Field Ablation to Treat Atrial Fibrillation: One-Year Outcomes From the MANIFEST-PF Registry.Circulation. 2023; 148: 35-46https://doi.org/10.1161/CIRCULATIONAHA.123.064959Google Scholar However, two cases of acute kidney injury (AKI) secondary to hemolysis after PFA have recently been reported after an uncommonly high number of applications.2Venier S. Vaxelaire N. Jacon P. et al.Severe acute kidney injury related to haemolysis after pulsed field ablation for atrial fibrillation.Europace. 2023; 26euad371https://doi.org/10.1093/europace/euad371Google Scholar,3Mohanty S, Casella M, Compagnucci P, et al. Acute Kidney Injury Resulting From Hemoglobinuria After Pulsed-Field Ablation in Atrial Fibrillation: Is it Preventable? JACC Clin Electrophysiol. doi:10.1016/j.jacep.2023.12.008Google Scholar Similarly, a subsequent pilot study reported the occurrence of AKI in 4/28 patients after PFA for AF.3Mohanty S, Casella M, Compagnucci P, et al. Acute Kidney Injury Resulting From Hemoglobinuria After Pulsed-Field Ablation in Atrial Fibrillation: Is it Preventable? JACC Clin Electrophysiol. doi:10.1016/j.jacep.2023.12.008Google Scholar We aimed to compare the incidence of AKI and hemolysis after catheter ablation of AF using radiofrequency energy (RFA), cryo-balloon energy (CBA) and PFA using a pentaspline catheter in a large patient population. We enrolled patients undergoing catheter ablation of AF in a prospective registry in a tertiary referral center between April 2010 and February 2024. Patients underwent pulmonary vein isolation using RFA (Thermocool or Smarttouch SF, Biosense Webster), CBA (Arctic Front, Medtronic or PolarX, Boston Scientific) or PFA (FARAPULSE, Boston Scienfitic) as previously described.4Badertscher P. Weidlich S. Knecht S. et al.Efficacy and safety of pulmonary vein isolation with pulsed field ablation vs. novel cryoballoon ablation system for atrial fibrillation.Europace. 2023; 25: euad329https://doi.org/10.1093/europace/euad329Google Scholar,5Badertscher P. Weidlich S. Serban T. et al.Pulsed-field ablation versus single-catheter high-power short-duration radiofrequency ablation for atrial fibrillation: Procedural characteristics, myocardial injury, and mid-term outcomes.Heart Rhythm. 2023; 20: 1277-1278https://doi.org/10.1016/j.hrthm.2023.05.007Google Scholar Blood samples, including renal parameters and hemolysis indicators, were obtained before the procedure and the day after the procedure. AKI was defined as an increase in serum creatinine by 26.5 μmol/L (equals 0.3 mg/dL) from baseline creatinine within up to 10 days after the procedure. The study was approved by the local ethics committees and adhered to the Helsinki Declaration. A total of 2570 patients (median age 64 years, 29.4% female) underwent catheter ablation for AF from April 2010 to February 2024: 1707 (66.4%) were treated with RFA, 557 (21.7%) using CBA and 306 (11.9%) using PFA. Median duration of ablation was 1669 (IQR 1207, 2164) sec for RFA, 1046 (IQR 840, 1451) sec for CBA and, 80 (IQR 48, 85) sec (32 (IQR 19, 34) applications) for PFA. AKI was found in 73 (4.3%), 10 (1.8%) and 3 (1.0%) patients treated with RFA, CBA and PFA, respectively, p=0.001. There was a statistically significant positive correlation for the RFA group between the ablation duration and the creatinine level after the procedure (p<0.001, r2=0.0063), while there was no positive correlation for the CBA (p=0.926, r2=-0.0021) and PFA (p=0.324, r2=0.0021) group (Figure). At least two hemolysis indicators (bilirubin, LDH or urea levels) were elevated the day after the procedure in 12.4%, 11.8% and 13.5% in the RFA, CBA and PFA group, respectively, p=0.819. Having at least two elevated hemolysis markers was positively correlated with AKI after procedure, p<0.0001. LDH levels were elevated in 40.1%, 38.1% and 33.9% in the RFA, CBA and PFA group, respectively, p=0.173. The three cases of AKI after PFA received a total of 86, 32 and 30 PFA applications; 2/3 cases demonstrated elevated LDH levels and one had elevated urea and bilirubin levels. Their maximal creatinine levels were 158, 171 and 188 μmol/l respectively. In this large cohort of 2570 patients undergoing catheter ablation of AF, we found a very low incidence of AKI for PFA with 1.0%, which was lower than for the other energy sources. Unspecific hemolysis indicators such as LDH were elevated in 1/3 of patients after ablation, irrespective of the used modality for ablation. Dialysis was never necessary. Previous studies suggested that the amount of hemolysis increased with the number of PFA applications. Of note, the two patients with severe AKI after PFA from the first report were treated with 174 and 126 applications, respectively, and the four patients with AKI after PFA from the second report were treated with a median of 94 applications. In comparison, our 306 PFA patients received a median of 32 applications. Considering a non-linear correlation between the total number of applications and creatinine levels post-procedural, we may have missed a correlation due to the small number of patients receiving more applications. The study's limitations include the non-randomized comparison and the lack of hemolysis-specific markers like haptoglobin. AKI is rare when PFA is used in a standardized fashion with no extensive high number of applications and is lower than after thermal ablation.