The FIRM Study Oslo will in two sequential within-patient trials investigate the efficacy of focal impulse and rotor modulation (FIRM) as a stand-alone procedure in the treatment of paroxysmal and persistent atrial fibrillation, evaluated by continuous pre- and post-procedural heart rhythm monitoring.

After a pilot/implementation study consisting of 10 patients with paroxysmal atrial fibrillation (AF); 20 patients with paroxysmal AF will be included in a within-patient trial. This study will be followed by a similar comparison in 20 patients with persistent or longstanding persistent AF.

The AF driving sources will be visualized by a novel sequential bi-atrial panoramic contact mapping technique. Unipolar signals will be recorded by a 64-polar basket catheter (FIRMap®, Topera. Inc.), then processed and the activation patterns visualized (RhythmView® 3D Electrophysiologic Mapping System, Topera, Inc.).

Focal impulse and rotor modulation (FIRM) will then be performed with standard irrigated radio frequency catheter ablation until rotor or focal impulse elimination is confirmed by repeat FIRM mapping.

Treatment efficacy will be assessed with continuous heart rhythm monitors (Reveal XT®, Medtronic, Minneapolis, USA) implanted 3 months prior to ablation, and freedom from AF defined as AF burden <1% at follow-up at 12, 24 and 30 months.

Inclusion Criteria:

• Paroxysmal atrial fibrillation despite of at least one Class I or Class III antiarrhythmic drug and/or previous conventional ablation (pulmonary vein isolation).
• At least one episode of paroxysmal atrial fibrillation should be documented by rhythm strip, ECG or implanted monitor during the last 6 months prior to ablation.

Exclusion Criteria:

• Significant structural heart disease (including symptomatic coronary heart disease; prosthetic mitral or tricuspid valve; congenital heart disease where abnormality or its correction prohibits or increases the risk of ablation).
• Intracardiac thrombus, tumor or dense contrast on TEE.
• Contraindication to anticoagulant therapy (heparin, warfarin, dabigatran and rivaroxaban).
• Anaphylactic allergy to contrast media.
• Poor general health resulting from other disease.
• Inability or refusal to provide written informed consent for the study.