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

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

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

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 control group. Ablation was performed using a commercially available PFA system comprising a generator, a 13.8 Fr steerable sheath and a 12 Fr over-the-wire ablation 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. In cases of failed PV isolation another complete cycle of 8 impulses per vein was delivered. A pre- and post-ablation electroanatomic map was performed in every patient. In patients with posterior wall low voltage areas, impulses were delivered aiming at posterior wall isolation (PWI). The procedural endpoint was complete PVI with demonstration of entrance and exit block of all PVs and isolation of the posterior wall if attempted.

The study group consisted of 23 patients (43.5% males, mean age 56.7±7.8 years) with HCM. Persistent AF was present in 8 patients (34.8%). Mean left ventricular ejection fraction was 56.3±7.8%, mean end diastolic interventricular septum diameter 20.1±2.5 mm and mean left atrial volume index 59.9±17.9 ml/m². 23 patients without HCM were matched. Mean procedural duration for the study group was 58.1±4.5 minutes with a mean fluoroscopy time of 9.5±3.0 minutes. Four patients (17.4%) showed incomplete PV isolation during remapping and underwent repeat PFA. Five patients (21.7%) showed low-voltage at the posterior wall during 3D sinus-rhythm mapping and underwent PWI with 14.7±11 impulses. 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. Four patients (17.4%) experienced recurrent persistent AF during follow-up of 365.7±62.4 days in the study group, which was comparable to 2 patients (8.7%) with arrhythmia recurrence in the control group (p=0.76).

3D-guided PFA in HCM patients is associated with high acute success rates. Mid-term follow-up showed modest arrhythmia recurrence rates. However, larger trials with longer follow-up periods are necessary in this challenging patient cohort.