Pulmonary vein isolation (PVI) using the cryoballoon has been proven equal to RF-PVI and is widely used. High Power Short Duration Ablation in RF-PVI has been successfully tested in several trials. Prospective data comparing both strategies is lacking.

This trial will compare acute success rates, safety and foremost long-term outcome of two different PVI strategies (HPSD-PVI vs. cryo-PVI).

In several trials and real-life data pulmonary vein isolation (PVI) using the cryoballoon technique has been proven equal to RF-PVI for the treatment of paroxysmal atrial fibrillation (PAF). Due to the "single-shot character" of the device and shorter procedure times the cryoballoon is being widely used for PVI within the last years. However, additional endpoints such as "non-excitability" of the ablation line and consecutive arrhythmias may not be targeted properly by this device also lacking a detailed contact map to evaluate potential fibrotic areas.

For the past decade, the use of RF energy for successful PVI has been the "gold standard". However, ablation time and potential gaps within the circumferential ablation line are still an issue. High power (70 Watts) over short duration (7s) (HPSD) is a recently introduced RF-PVI concept. It has been shown to be as effective as conventional RF-PVI with equal safety features, shorter procedure durations and a superior long-term outcome. Therefore, HPSD-PVI in combination with the endpoint of "non-excitability" is potentially superior with regard to freedom of atrial arrhythmia during long-term FU compared to cryo-PVI with similar procedure times.

So far, randomized prospective data comparing HPSD versus cryo-PVI are lacking.

The aim of this prospective randomized study is to compare acute success rates, safety and foremost long-term outcome of two different PVI strategies (HPSD-PVI vs. cryo-PVI):

1. To find the safest and most effective treatment strategy for PAF patients. 2. To evaluate the risk of complications for both treatment strategies.

3. Evaluation of procedure endpoints like duration, costs and radiation dose.

The present study is a mono-center prospective randomized study enrolling 170 patients with PAF and no prior Ablation for AF.

Patients will be randomized to one of the following groups. Group A: Cryo-Ablation PVI will be performed using a Cryo-balloon. Group B: High-Power-Short-Duration PVI will be performed using HPSD RF-ablation. (70W over 5s posterior and 7s anterior) Catheter ablation procedures will be performed with commercially available devices including 3D mapping systems (EnSite, Abbott) and irrigated radiofrequency current (RFC) ablation or cryothermal balloon ablation (Arctic Front Advance Pro, Medtronic).

The study shall start enrolling patients in April 2021. The last patient shall be enrolled in January 2023. Since follow-up is 12 months, end of study is planned for January 2024.

Inclusion Criteria:

• Symptomatic non-valvular atrial fibrillation with no prior ablation with an indication for re-ablation according to current guidelines.
• Age 18-85 years.
• Patient is able to provide informed consent and is willing to comply with the study protocol.

Exclusion Criteria:

• Contraindications for left atrial ablation
• History of interventional or surgical AF-ablation
• History of stroke during the past 12 months
• BMI >40kg/m2
• History of mitral valve surgery
• Severe mitral valve regurgitation
• Inability to be treated with oral anticoagulation
• Presence of intracardiac thrombi
• Contraindication or absolute indication for one of the two strategies
• Pregnancy
• Participation in other clinical studies
• Unwilling to follow the study protocol and to attend follow-up visits