Pulsed-field energy ablation (PFA) was significantly associated with hemolysis compared to radiofrequency ablation (RFA) following pulmonary vein isolation (PVI), according to the results of a study presented at Heart Rhythm 2024 and simultaneously published in JACC: Clinical Electrophysiology.

The prospective, nonrandomized, single-center study, conducted between November 2023 and February 2024 in Prague, assigned 70 adult patients with symptomatic paroxysmal or nonparoxysmal atrial fibrillation (AFib) indicated for a first-ever AFib ablation procedure (47% women, mean age 64.7 years; 51.4% with paroxysmal AFib) to either PFA or RFA (47 PFA and 23 RFA) based on their position on the waiting list and the center's anesthesia schedule.

Blood samples were taken at three points: at the beginning of the procedure, at the end of the ablation procedure and one day after ablation. The concentration of red blood cell microparticles (RBCµ), a marker of hemolysis, were assessed at each draw using flow cytometry. Lactate-dehydrogenase (LDH), haptoglobin and indirect bilirubin, all further markers, were measured at baseline and at 24 hours.

Results showed that the concentration of RBCµ increased at the end of the procedure for both groups, but compared to baseline levels this increase was about 12-fold higher with PFA vs. about two-fold higher with RFA. In both groups, RBCµ returned to baseline within 24 hours.

By 24 hours post procedure, with PFA, LDH and indirect bilirubin significantly increased (2.70 to 4.67 µkat/L and 10.3 to 14.1 µmol/L, respectively) and haptoglobon was significant decreased (12.0 vs 0.44 g/L). With RFA, LDH increased (2.89 to 3.08 µkat/L) and haptoglobin decreased (1.31 to 1.17 g/L) but not to the same extent as PFA. There was no significant change in indirect bilirubin concentration.

Patients assigned to PFA were further divided into PVI-only and PVI-plus (patients who underwent additional ablation) subgroups (22 PVI-only, 25 PVI-plus). PVI-plus was associated with a significantly higher number of PF applications (67.3 vs. 36.4 in PVI-only). Between these two subgroups, the peak concentration of RBCµ at the end of the procedure was higher in PVI-plus vs. PVI-only (924.2 vs. 657.1 RBCµ/µL; p=0.007). At 24 hours, for PVI-plus patients, the concentration of LDH was significantly higher (5.24 vs. 4.21 µkat/L; p<0.001) and haptoglobin significantly lower (0.35 vs. 0.62 g/L; p=0.04). There was no difference in the indirect bilirubin concentration between the two groups.

Pavel Osmancik, MD, PhD, et al., write they were, "not able to characterize the 'safe' number of PF applications, i.e., the number of PF applications associated with acute renal impairment." They continue that the risk of postprocedural renal injury depends not only on the level of hemolysis, but on pre-procedural renal status, and hydration. "However, it was shown that RBCµ concentrations increased with higher number of PF pulses; therefore, a large number of PF applications should be avoided, especially in patients with pre-existing renal dysfunction. On the other hand, with a number of 70 PFA lesions, the likelihood of significant renal injury is uncommon."