Rationale: Atrial fibrillation (AF) is a highly prevalent cardiac arrhythmia. AF is classified as paroxysmal or persistent AF, based on the duration and persistency of the arrhythmia. Despite state-of-the-art pharmacological therapies targeting the ventricular rate or aiming to restore sinus rhythm, many patients with persistent AF stay symptomatic. Catheter ablation, endocardial pulmonary vein isolation (PVI) in particular, is the most commonly applied approach to treat drug refractory persistent AF, but particularly in this patient group results are modest. Alternatively, the PVs can be approached epicardially by thoracoscopic surgery to isolate the PVs. This approach is more efficacious, at the cost of a more invasive procedure and longer hospital stay. However, no studies have been conducted comparing catheter with thoracoscopic ablation in patients with persistent AF as a primary invasive procedure after failing treatment with anti-arrhythmic medication.

Objective: This current study aims to assess a patient specific therapy plan for patients with persistent AF by randomizing thoracoscopic versus catheter ablation for PVI without adjuvant substrate ablation in those patients.

Study design: This is a prospective, non-blinded randomized multicenter study. Subjects will be randomized (1:1) to one of the two study-arms (thoracoscopic surgical or catheter PVI). The follow-up will last 5 years, with heart rhythm monitoring at three and six months, one year and yearly in the following years. In case AF recurs during the first year, the subject will receive the treatment of the otherother arm, or according to patient choice or clinical routine.

Study population: Patients with an indication for invasive treatment of persistent AF.

Intervention: Thoracoscopic surgical or catheter PVI without additional lesions.

Inclusion Criteria:

• Age is between 18 and 80 years
• Persistent AF as defined following the ESC 2016 Guidelines, evidenced by 1) ongoing AF on the ECG or 2) documentation of AF necessitating cardioversion.
• AF documented by ECG or Holter < 1 year ago.
• At least one class I or III anti-arrhythmic drug in standard dosage has failed or is not tolerated.
• Left atrial volume index ≤ 45 ml/m2
• Legally competent and willing to sign the informed consent.
• Willing and able to adhere to the follow-up visit protocol.
• Life expectancy of at least 2 years.

Exclusion Criteria:

• Prior intervention (catheter ablation or minimally-invasive thoracoscopic ablation) for AF.
• AF is secondary to electrolyte imbalance, thyroid disease or other reversible or non-cardiovascular causes.
• Documentation of CTI dependent atrial flutter
• Valvular AF
• Paroxysmal AF
• Long standing Persistent AF, defined as AF continuously present for longer than 1 year.
• Body mass index >35kg/m2
• NYHA class IV heart failure symptoms or left ventricular ejection fraction <35%.
• NYHA class III heart failure symptoms, unless caused or aggravated by AF.
• Myocardial infarction within the preceding 2 months.
• Active infection or sepsis (as evidenced by increased white blood cell count, elevated CRP level or fever >38,5 °C).
• Known and documented carotid stenosis > 80%
• Planned cardiac surgery for other purposes than AF.
• Pregnancy or child bearing potential without adequate anticonception.
• Requirement of anti-arrhythmic drugs for ventricular arrhythmias.
• Presence of intracardiac mass or thrombus (discovery of any thrombus or intracardiac mass after signing of the informed consent will result in withdrawal of the subject from the study)
• Co-morbid condition that possesses undue risk of general anesthesia or port access cardiac surgery (in the opinion of the operator).
• History of previous radiation therapy on the thorax
• Circumstances that prevent follow-up
• No vascular access for catheterization.
• History of previous thoracotomy.
• Factors precluding transseptal puncture for catheterization.