This clinical study evaluates the safety and efficacy of the treatment with the CoolLoop® cryoablation System (sclerotherapy of muscle tissue of the heart by freezing) in patients with atrial fibrillation (permanent atrial fibrillation excepted) over a follow-up period of 36 months.

A further aim of this study is to evaluate the average duration of procedure and fluoroscopy times.

Inclusion Criteria:

• Age ≥ 18 years
• atrial fibrillation: permanent AF excepted
• ECG documented AF within the last 6 months
• patients planned for an ablation procedure and suitable and planned for treatment with the CoolLoop® cryoablation system
• signed and dated informed consent documented by the patient, indicating that the patient has been informed of all the pertinent aspects of the trial prior to study enrollment (patient has received a copy of the ICF)

Exclusion Criteria:

• indication that the vascular system is not accessible through the left or right groin.
• indication that a transseptal puncture cannot be performed.
• any previous ablation or surgery due to AF.
• important comorbidities such as cardiovascular events within six months of enrollment or high-risk surgical patients.
• pregnant women at the time of the cryoablation procedure.
• any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from signing the Informed Consent Form.
• participation in interventional trials for cardiovascular devices or drugs.

Patients have to be planned and be suitable for an ablation procedure. The decision to treat the patients with the CoolLoop® cryoablation System has already been made in advance by the Investigator. Informed consent has to be obtained before the ablation procedure.