Atrial fibrillation (AF) is the most common heart rhythm disorder affecting 2-4% of the adult human population. AF is a disturbance in the electrical impulses of the heart - an electrical disturbance commonly originating from the pulmonary veins.

Normalization of the heart rhythm with anti-arrhythmic drugs often fail and is frequently associated with side effects. Therefore, a treatment termed ablation by catheters via an inguinal vein has been devised and is increasingly being used for the treatment of AF. The cornerstone of this treatment is electrical isolation of the pulmonary veins so that the nocuous electrical impulses from the pulmonary veins cannot cause a disturbance in the heart rhythm and initiate episodes of AF. This treatment is called pulmonary vein isolation (PVI). Recent studies have shown that PVI is better than anti-arrhythmic drug treatment in the prevention of recurrence of AF, but despite substantial improvements in techniques and tools only 60-70% are cured from AF by a single PVI procedure, and in around 80% of patients who require additional catheter ablation, durable isolation of all the pulmonary veins has not been achieved. Improved tools for durable PVI are therefore required.

A novel catheter to achieve PVI called the HELIOSTAR™ radiofrequency balloon ablation catheter has shown promising clinical results with a favorable safety profile, but the durability of PVI has not been evaluated. Therefore, we aim to investigate the long-term durability of PVI by the radiofrequency balloon and the clinical outcome following the procedure.

In this study, patients with AF referred for catheter ablation will undergo an initial PVI treatment using the radiofrequency balloon catheter. All patients will undergo a repeat electrophysiology (EP) study after 4-6 months to determine to durability of PVI. Patients will be issued with a 48-hour heart rhythm monitor at 3 and 12 months after the initial PVI. Patients-reported effects on quality of life by AF related symptoms will be evaluated using a specialized questionnaire provided approximately every third month throughout the 12 month follow-up.

The study is a single-arm prospective cohort study in 45 patients referred for AF ablation that will assess the durability of PVI, freedom from atrial tachyarrhythmia (ATA) recurrence and patient reported quality of life following PVI by radiofrequency balloon catheter ablation.

All patients, irrespective of ATA recurrence, will undergo a repeat EP study 4-6 months after initial PVI for the assessment of PVI durability. Recurrence of ATA after the initial PVI will be evaluated by 48-hour ambulatory electrocardiography (ECG) monitoring following a 3-months blanking period after the PVI procedure, and effect on quality of life will be evaluated by questionnaires at baseline, 3 months after the initial PVI, and at the time of the repeat procedure.

Recurrence of ATA after the repeat EP study will be evaluated by 48-hour ambulatory ECG monitoring 12 months after the initial PVI, and effect on quality of life will be evaluated by additional questionnaires at 9 and 12 months after the initial PVI.

In patients with symptoms of potentiel ATA outside the protocolled ambulatory ECG monitoring periods, ECG diagnostics appropriate for the duration and frequency of episodes with symptoms will be utilized.

Inclusion Criteria:

• Documented AF
• Clinical indication for ablation
• First time AF ablation
• Scheduled for PVI only

Exclusion Criteria:

• Contraindication for ablation
• Inability to give informed consent
• Documented atrial flutter or any other arrhythmia requiring ablation in addition to PVI
• Known esophageal or nasopharyngeal pathology that would preclude insertion of an esophageal temperature probe
• Severe asthma that would preclude adenosine injections for assessment of dormant conduction