This randomised study will compare pulsed field ablation and cryoballoon ablation with respect to ablation lesion quality as assessed by late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) at 3 months post-ablation. Patients scheduled for first-time AF ablation will be randomised in a 2:1 fashion to receive PVI-only, either by pulsed field ablation (Farapulse Pulsed Field Ablation System, Boston Scientific) or cryoballoon ablation (Medtronic Cryoballoon Ablation System).

Pulmonary vein isolation (PVI) using catheter ablation has become a cornerstone in the treatment of AF and is considered the most effective therapy today. Catheter ablation has been mostly performed employing thermal energies, with radiofrequency and cryo-balloon ablation being the best validated most widely applied modalities. Despite substantial technological and procedural advances that have improved efficacy, efficiency and safety of AF ablation in recent years, long-term durability of ablation lesions is still not satisfactory, and rare but potentially life-threatening procedure-related complications like cardiac tamponade or atrio-esophageal fistula remain a concern. In addition, phrenic nerve palsy complicates a relevant proportion of procedures, particularly in cryo-ablation.

The novel non-thermal ablation method of pulsed field ablation holds great promise in that respect. Pulsed field ablation achieves permanent cell death through electroporation, which appears to provide a unique selectivity for cardiomyocytes and to spare surrounding tissues composed of other cell types, thus minimising the risk of collateral damage.This method has already been introduced into routine clinical practice and is established in many centers worldwide. A large number of studies have confirmed safety and efficacy of pulsed field ablation for pulmonary vein isolation in the context of AF and found significant reductions in ablation times. However, the putative benefits regarding efficacy, efficiency and safety remain to be proven in randomised controlled trials.

Against this background, the investigators aim to perform a randomised clinical trial comparing pulsed field ablation with thermal cryo-balloon ablation with respect to efficacy, effectiveness and safety. Patients scheduled for first-time AF ablation will be randomised in a 2:1 fashion to receive PVI-only, either by pulsed field ablation (Farapulse Pulsed Field Ablation System, Boston Scientific) or cryoballoon ablation (Medtronic Cryoballoon Ablation System). The primary outcome of this trial will be ablation lesion quality as assessed by late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) at 3 months post-ablation.

Inclusion Criteria:

• Patients scheduled for first-time atrial fibrillation catheter ablation

Exclusion Criteria:

• age <18 years
• long-standing persistent atrial fibrillation
• prior left atrial ablation
• pregnancy or lactation
• reduced left ventricular ejection fraction
• GFR <30%
• BMI >35%
• left atrial diameter >55 mm
• cardiac implantable electronic device