This study evaluates the effect of catheter ablation of ganglionated plexi (GP) for the treatment of adult patients with atrial fibrillation heart arrhythmias. The location of GP will be demonstrated by a novel nuclear imaging cardiac camera. 3D images from the cardiac camera will guide the GP ablation procedure.

Catheter ablation procedures are nowadays routine procedures in patients with drug-refractory atrial fibrillation (AF). However, ablation success for patients even in the early stages of AF is currently only around 70% and may require multiple procedures.

The intrinsic cardiac autonomic nervous system (ANS), which forms a neural network, has been shown to be a critical element responsible for the initiation and maintenance of AF. Autonomic inputs to the heart converge at several locations; these convergence points are typically embedded in the epicardial fat pads and form ganglionated plexi (GP) that contain autonomic ganglia and nerves. In human hearts, there are at least 7 GP and the 4 major left atrial GP are located around the antrum of the pulmonary veins (PVs). High-frequency stimulation (HFS; 20 Hz, 10-150 V and pulse width 1-10 ms) can localize GP during an invasive electrophysiology (EP) study.

A novel dedicated cardiac nuclear imaging camera with solid-state detectors (D-SPECT, Spectrum Dynamics) has demonstrated significantly improved sensitivity and image resolution and can provide novel imaging information on previously 'invisible' structures like the GP. Using this 3D image information to guide GP ablation could significantly facilitate AF ablation and result in improved ablation outcomes.

Inclusion Criteria:

• Paroxysmal or early persistent atrial fibrillation with ongoing AF for less than 1 week
• Able to give written informed consent
• Age >18 years old and ≤ 80 years
• Fulfil established clinical criteria for catheter ablation of atrial fibrillation
• Normal left ventricular (LV) ejection fraction and no evidence of significant structural heart disease

Exclusion Criteria:

• Reversible cause of atrial fibrillation
• Recent cardiovascular event including transient ischaemic attack (TIA)
• Intolerance or unwillingness to oral anticoagulation with Warfarin
• Bleeding disorder
• Contraindication to computed tomography (CT) scan
• Presence of intracardiac thrombus
• Vascular disorder preventing access to femoral veins
• Cardiac congenital abnormality
• Severe, life threatening non cardiac disease
• Active malignant disease or recent (<5 years) malignant disease
• Presence of atrial septal defect (ASD) or patent foramen ovale (PFO) closure device
• Unable or unwilling to comply with follow-up requirements
• Patients on amiodarone until less than 3 months prior to the screening visit
• Left atrium size > 5.5 cm on parasternal diameter in transthoracic echocardiography (TTE)
• Renal impairment
• Pregnancy