This is a clinical study where the investigators will assess the efficacy of a single cryoballoon application per vein guided by a multipolar recording catheter as compared with a conventional technique with 2 cryoballoon applications for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF).

This is a prospective, randomized clinical study performed at one centre. The objective is to assess the efficacy of a single cryoballoon application per vein guided by a multipolar recording catheter as compared with a conventional technique with 2 cryoballoon applications for pulmonary vein isolation in patients with atrial fibrillation (AF).

140 subjects with paroxysmal or persistent atrial fibrillation referred for their first AF ablation procedures will be enrolled.

Recruitment, ablation and follow-up will be performed at Dep of Cardiology in Uppsala University Hospital, Uppsala, Sweden.

Study duration is 2 years with 12--months enrolment period and 1 year follow-up per subject.

Pulmonary vein isolation (PVI) will be performed using the Arctic Front Advance cryoballoon ablation catheter. Patients will be randomized to a single cryoballoon application guided by a multipolar recording catheter or to a conventional technique with 2 cryoballoon applications. After cryoballoon ablation of all pulmonary veins, PV conduction block will be assessed by a separate circular mapping catheter. Acute procedural success is defined as complete electrical isolation of a pulmonary vein assessed by entrance and exit block, including 20 minutes waiting time. Complications and duration of the procedure will be assessed.

Patients will be followed at three, six and 12 months after the ablation procedure. A 12 lead ECG, a 7 day Holter monitoring, quality of life (EQ5D) and EHRA score, will be performed at baseline, 6 and 12 months. as well as Biomarkers including nTproBNP and troponin I, will be performed at baseline, and at 6 and 12 months (only nTproBNP). Predictive variables for successful outcome/AF recurrence will be analysed.

The frequency of symptomatic recurrence of AF and number of reablations will be compared at 6 and 12 months, and in those requiring a redo ablation procedure the status of PV reconduction will be assessed.

Inclusion Criteria:

• Patients with paroxysmal or persistent AF verified by ECG
• Patients with symptoms corresponding to at least Europe Heart Rhythm Association (EHRA) score 2.

Exclusion Criteria:

• Sinus rhythm cannot be maintained for at least one hour after an electrical cardioversion.
• Congestive heart failure with New York Heart Association (NYHA) class 3 or more.
• Left ventricular ejection fraction < 35% not secondary to AF with inadequate rate control, according to the judgement of the investigator.
• Left atrial diameter ≥ 55 mm judged by transthoracic echocardiography.
• Prior AF ablation procedure.
• Longstanding persistent AF
• AF secondary to a transient or correctable abnormality including electrolyte imbalance, trauma, recent surgery, infection, toxic ingestion, and uncontrolled thyroid disease as well as AF triggered by other uniform supraventricular tachycardia.
• Contraindication to treatment with anticoagulants.
• Significant valvular disease or planned cardiac intervention.
• Hypertrophic cardiomyopathy.
• Recent cardiac disease states within the last 6 months; unstable angina, acute myocardial infarction, revascularisation procedures, valve disease
• Implantable cardioverter-defibrillator (ICD), cardiac resynchronization therapy (CRT) device.
• Dual chamber- and single chamber-pacemaker when the patient is pacemaker dependent on ventricular level
• Patients with contraindications for transseptal catheterization or appropriate vascular access is precluded.
• Renal failure requiring dialysis or abnormalities of liver function tests.
• Participant in investigational clinical or device trial.
• Unwilling or unable to give informed consent or inaccessible for follow-up and psychological problem that might limit compliance.
• Active abuse of alcohol or other substance which may be causative of AF and/or might affect compliance.