The purpose of this randomized, controlled trial is to investigate whether coronary computed tomography (CT) angiography prior to catheter ablation and derived treatment (medical anti-ischemic and multimodality treatment and/or mechanical revascularization) can improve clinical outcomes in patients with atrial fibrillation undergoing catheter ablation.

A sub-study will investigate the effect of different ablation strategies on clinical outcomes in patients with atrial fibrillation undergoing catheter ablation.

The study is an investigator-initiated, prospective, randomized, unblinded, controlled trial to investigate whether coronary CT angiography prior to catheter ablation and derived treatment can improve clinical outcomes in patients with atrial fibrillation undergoing catheter ablation. The study population will consist of approximately 852 patients aged 18 years and above referred for a catheter ablation treatment for atrial fibrillation at Gentofte Hospital in Denmark. All participants included in the study will have a coronary CT angiography and coronary artery calcium (CAC) scoring performed as an amendment to the standard CT scan of the heart for mapping of the atria prior to catheter ablation. The participants are randomized 1:1 to either have the coronary CT angiography analyzed or not at the time of catheter ablation. According to the results of the coronary CT angiography in the intervention group, subsequent actions may include intensified multimodality medical treatment or referral to further functional imaging or invasive coronary angiography and possibly mechanical revascularization according to clinical guidelines. The study will be completed when each patient has been followed for at least 1 year. After ablation, an insertable cardiac monitor will be implanted in participants to monitor the heart rhythm continuously throughout the study period.The primary endpoint is time to first documented recurrence of atrial tachyarrhythmia lasting >30 seconds between 91 days after ablation and end of follow-up.

All participants meeting the eligibility criteria and enrolled in the FIBCAG main study are eligible to participate in a sub-study with the purpose of investigating different catheter ablation strategies by sub-randomizing participants to different ablation protocols depending on whether they have paroxysmal or persistent atrial fibrillation or they are undergoing first or redo ablation:

1. If they have paroxysmal atrial fibrillation, the participants will be randomized 1:1 to either pulmonary vein isolation (PVI) or PVI plus posterior wall isolation (FIBCAG-PAF).
2. If they have persistent atrial fibrillation, the participants will be randomized 1:1 to either PVI or PVI plus posterior wall isolation, mitral isthmus block, cavotricuspid isthmus block and intercaval linear ablation (FIBCAG-PeAF).
3. If they are undergoing reablation, the participants will be randomized 1:1 to either PVI or PVI plus posterior wall isolation, mitral isthmus block, cavotricuspid isthmus block and intercaval linear ablation (FIBCAG-Redo).

All ablation procedures and strategies are currently standard interventions in clinical care. Procedures are performed under general anesthesia or deep sedation based on availability, and patients are blinded to the method of ablation. PVI will be performed according to best current clinical practice using pulsed field ablation with a single shot device or by point-by-point ablation.

Inclusion Criteria:

• Age over 18 years.
• Referral for catheter ablation treatment (excluding AV-junction ablation) for atrial fibrillation (both paroxysmal and persistent atrial fibrillation) at the Department of Cardiology at Gentofte Hospital. Both first ablation and re-ablation treatments are included.
• The ability and willingness to provide written informed consent.

Exclusion Criteria:

• Known atherosclerotic cardiovascular disease (ASCVD).
• Ongoing treatment with statins.
• Contraindications for coronary CT angiography, e.g. contrast allergy
• Recent coronary CT angiography including CAC-score without positive findings <3 years prior to screening.
• Any surgical or medical condition, which in the opinion of the investigator, may place the patient at higher risk from his/her participation in the study, or is likely to prevent the patient from complying with the requirements of the study or completing the study.

Please contact the sponsor-investigator in case of any inquiries.