Evaluation of left atrial volume and function following pulsed-field ablation of atrial fibrillation: preliminary results of a prospective, observational study

Atrial fibrillation (AF) often leads to structural remodeling of the heart, increasing the risk of heart failure, stroke and death. The primary challenges remain the progression of atrial cardiomyopathy and AF recurrence after ablation. Pulsed-field ablation (PFA) is a novel, tissue-selective modality of catheter ablation of AF. Data regarding the effect of PFA beyond PVI is limited. Extensive radiofrequency ablation carries the risk of stiff left atrium (LA) syndrome, associated with pulmonary hypertension and symptoms of heart failure. Our goal was to investigate the effect of extensive PFA on LA function and development of stiff LA syndrome.

The aim of the study was to measure left atrial strain and fibrosis after AF ablation in two patient groups: PVI only and PVI plus additional ablation.

Patients with symptomatic AF who underwent PFA as an initial ablation between March 2023 and April 2024 were enrolled. The study groups consisted of patients who underwent pulmonary vein isolation only (PVI only) and those who had additional ablation of either two including the roof, mitral isthmus, posterior wall or anterior wall (PVI plus). The ablation strategy was left to the operating physician’s discretion. All patients were scheduled for speckle-tracking echocardiography, laboratory tests including fibrosis marker analysis and completion of a quality of life questionnaire.

Seventy-eight patients were enrolled with a median age of 63 (55-70) years, 50 (64%) were male. The scheduled tests were carried out a median 144 (97-171) days after the procedure. Patients in the PVI plus group (n=27; 35%) had significantly larger LA volume (p=0.042), lower LA reservoir strain (LArS, p=0.003), but higher LA contractile strain (p=0.007). LA stiffness measured by medial and lateral e/E' – to - LArS ratio showed reduced LA compliance (p<0.001 and 0.005, respectively). However, there was no difference in pulmonary artery systolic pressure (32.5 [28.5-39.8] vs. 30 [27.5-38.5], p=0.42) between the two groups. Quality of life measured by the AFEQT questionnaire was similar among the groups (p=0.55). The 12-month follow-up for AF freedom and fibrosis marker analyses are still ongoing.

Patients who underwent an extensive initial PFA had significantly higher LA reservoir strain and reduced LA compliance compared to the PVI only group with similar patient reported outcomes. Although LA stiffness was increased in PVI plus group, no clinical signs of stiff LA syndrome was observed.