Reduction in Arrhythmia Burden With Left Atrial Posterior Wall Ablation for Persistent AF

Inclusion criteria: * Age 18 to 80 (inclusive) * Patients with symptomatic advanced persistent AF, defined as: * AF which does not spontaneously terminate and requires medical intervention (antiarrhythmics or DCCV) to terminate, AND * Recurs following cardioversion, AND * Is associated with evidence of left atrial cardiopathy, defined as at least mild left atrial enlargement on imaging (echo, CT or MRI) as defined by standard values (for example British Society of Echocardiography or European equivalent) - in the event of uncertainty, Principal Investigator discretion is allowed. Exclusion Criteria * Any previous catheter (or surgical) ablation for AF (previous ablation for atrial flutter or focal atrial tachycardias are allowable) * An indwelling atrial septal defect occluder device or anatomical structure that pre-vents free access to the left atrium * Severe left ventricular systolic dysfunction (ejection fraction less than 35%) * Recent stroke/transient ischaemic attack within 3 months * Inability, unwillingness or absolute contraindication to taking an oral anticoagulant medication * Severe kidney function impairment (eGFR less than 30ml/min/1.73m2) * Morbid obesity with a body mass index ≥40 * Extreme frailty (a score of 7,8 or 9 on the Rockwood Clinical Frailty Scale) * Severe valvular heart disease of any kind as assessed by the investigator, with or without a prosthetic valve in place * Pregnancy