Short term biatrial remodeling after pulsed field ablation vs cryoablation: a comparative cardiac magnetic resonance volumetric and strain analysis

Background

Pulsed field ablation (PFA) is emerging as a non-thermal modality for Pulmonary vein isolation (PVI) in the treatment of atrial fibrillation (AF) demonstrating favorable clinical outcomes when compared to traditional radiofrequency and cryoablation(1). While PVI reduces AF burden and may promote reversal of atrial cardiomyopathy, ablation lesions can adversely affect left atrial compliance and function. (2) (3) The impact of PFA on atrial structural and functional remodeling, particularly in relation to cryoablation, remains underexplored through advanced imaging modalities.

Purpose

To compare the impact of pulsed field ablation to cryoablation for AF on right and left atrial volumes and functions by cardiac magnetic resonance imaging (CMR).

Methods

This comparative cohort study included 30 patients with AF who underwent PVI using either PFA ( n=13) or cryoablation (n=17) at a single center. Patients with prior atrial ablation or significant structural heart disease, apart from AF induced cardiomyopathy, were excluded. Both procedures were done under fluoroscopy guidance with contrast injection to delineate pulmonary veins. PFA was done using pentaspline catheter using standard protocols(4). All patients underwent CMR before and 3–6 months after ablation to quantify biatrial volumes and strain parameters (reservoir, conduit and contractile). Comparisons between pre and post ablation parameters collectively and between both groups were made using appropriate tests. The primary analysis of post-ablation CMR parameters was performed using analysis of covariance (ANCOVA), adjusted for baseline values, atrial fibrillation type, and time to follow-up imaging.

Results

Baseline demographic and clinical characteristics were comparable between groups, except for a higher proportion of persistent AF in the PFA cohort and a shorter interval to follow-up CMR. PFA patients had significantly larger ventricular volumes at initial studies (Figure 1).

At follow-up, both groups exhibited significant reduction in left atrial expansion index, left atrial contractile ejection fraction and left atrial strain parameters. Meanwhile right atrial contractile ejection fraction and contractile strain showed marked improvement. (Figure 2, Panel A )

The analysis of changes of atrial parameters between the two groups demonstrated no statistically significant difference in the adjusted and unadjusted changes of atrial volumetric or functional parameters. (Figure 2 Panel B)

Conclusion

In our CMR based study, both PFA and cryoablation achieved comparable short-term atrial remodeling marked by enhanced right atrial contractility and declined LA functional parameters. Although PFA group had more advanced AF pattern and higher ventricular volumes, no significant differences were detected in right or left atrial parameters between the two modalities. Larger, randomized studies are warranted to confirm these findings.