Initial experience of electroanatomic mapping guided pulsed field ablation for atrial fibrillation ablation in patients with hypertrophic cardiomyopathy

Background: Freedom from atrial arrhythmia recurrence after pulmonary vein isolation (PVI) in patients with hypertrophic cardiomyopathy (HCM) remains a major challenge.

Aims: To report a high-volume experience on safety and effectivity of pulsed field ablation (PFA) in patients with HCM.

Methods: Consecutive patients with HCM undergoing first time PVI by PFA between 02/2022 and 11/2024 were prospectively enrolled. A cohort of patients without HCM undergoing PFA served as a control group. Ablation was performed using a commercially available PFA over-the-wire device with seamless changing between a “flower-like” and a “basket-like” pose. Electroanatomic mapping using a 3D-system and a spiral mapping catheter were performed in each patient before PFA. The general ablation protocol provided 8 PFA impulses for each pulmonary vein (PV) with 4 impulses in the basket-like shape of the device and 4 impulses in the flower-like shape. An electroanatomic map was performed in every patient after PFA. In patients with posterior wall low voltage, impulses were delivered aiming at posterior wall isolation. The procedural endpoint was complete PVI with demonstration of entrance and exit block of all PVs and isolation of the posterior wall if attempted. Follow-up comprised of patient visits, ECG and Holter-ECG recordings after 3, 6 and 12 months.

Results: The study group consisted of 23 patients (43.5% males, 56.7±7.8 years) with HCM. 8 patients had persistent AF (34.8%). Left ventricular ejection fraction was 56.3±7.8%, end diastolic interventricular septum diameter 20.1±2.5 mm and left atrial volume index 59.9±17.9 ml/m². 23 patients without HCM were matched regarding age, gender, type of AF, left ventricular function and follow up duration to serve as a control group. Procedural duration in the study group was 58.1±4.5 minutes with a fluoroscopy time of 9.5±3.0 minutes. 4 patients (17.4%) showed incomplete PVI during remapping and underwent repeat PFA. Five patients (21.7%) showed posterior low-voltage areas during 3D sinus-rhythm mapping. Posterior wall isolation was performed in these patients with a mean of 14.7±11 impulses with a maximum of 30 applications in one case. Mean number of total impulses per patient was 45.8±16.1 in the study group. In the control group procedural duration was 49.3±2.5 min (p=0.1) with a significant lower number of ablation impulses per patient as compared to the study group (33.5±5.3, p=0.01). No periprocedural complications occurred in both cohorts. Four patients (17.4%) experienced recurrent persistent AF during a follow-up period of 365.7±62.4 days in the study group, which was comparable to 2 arrhythmia recurrence in the control group (8.7%, p=0.76).

Conclusions: 3D-guided PFA in HCM patients is associated with high acute success rates. Mid-term follow-up showed modest arrhythmia recurrence rates comparable to patients without HCM. However, larger trials with longer follow-up periods are necessary in this challenging patient cohort.