The FIRE AND ICE II Trial (Pilot) is the pilot phase of a prospective, randomized, single-blinded, multi-center, interventional post-market clinical trial, comparing efficacy and safety of isolation of the pulmonary veins (PVI) using a Cryoballoon catheter or radiofrequency ablation with a ThermoCool® Smarttouch® catheter in subjects with persistent atrial fibrillation (AF).

60 patients with persistent AF will be randomized 1:1 between Cryoballoon ablation and Radiofrequency ablation in the FIRE AND ICE II Trial Pilot at 5 clinical sites in Europe.

The data collected within the pilot phase will be reviewed and a decision on extending the trial with an extended number of patients and sites as main phase will be taken.

Key Inclusion Criteria

• Documentation of symptomatic persistent AF (following the European Society of Cardiology (ESC) guideline 2016) defined as: Persistent AF - AF that lasts longer than 7 days, including episodes that are terminated by cardioversion, either with drugs or by direct current cardioversion, after 7 days or more
• Date of first diagnosis of persistent AF within the last 12 months preceding the date of screening
• Documented treatment failure or intolerance of at least one Class I or Class III antiarrhythmic drug

Key Exclusion Criteria

• Known pre-existing hemi-diaphragmatic paralysis
• Prior left atrial ablation or surgical procedure (including left atrial appendage closures)
• History of right atrial flutter, not ablated prior to enrollment
• Any cardiac surgery, myocardial infarction, percutaneous coronary intervention or coronary artery stenting which occurred within the 3 months before the eligibility assessment
• Unstable angina pectoris
• Primary pulmonary hypertension
• Any condition contraindicating chronic anticoagulation
• Any cerebral ischemic event (stroke or transient ischemic attack [TIA]) which occurred within the 6 months before the consent date
• Presence of any cardiac prosthetic valves
• Long-standing persistent AF lasting for ≥ 1 year (even when it is decided to adopt a rhythm control strategy)
• New York Health Association (NYHA) class III or IV heart failure and/or documented left ventricular ejection fraction (LVEF) < 40% measured by acceptable cardiac testing (e.g. TTE)
• Acute cardiac condition, including endocarditis, pericarditis or pericardial effusion
• Presence or likely implant of a permanent pacemaker, biventricular pacemaker or any type of implantable cardiac defibrillator (with or without biventricular pacing function) within 12 months

Single-blinded; participants will be blinded to the treatment group. Investigators will be blinded on study specific diagnostics used in the trial; Endpoint Review Committee will be blinded to the treatment group.