The main aim of the research is to investigate whether patients undergoing pulmonary vein isolation with catheter ablation for persistent atrial fibrillation (AF) will have lower rates of AF recurrence than those treated by DC cardioversion without an ablation procedure.

After adequate stroke prevention (e.g. anticoagulation) and rate control, the optimum strategy for patients who continue to be symptomatic with persistent AF has not been established. Cardioversion with antiarrhythmic medication is commonly used as a first-line rhythm control strategy despite very high recurrence rates of index arrhythmia and high serious complications associated with this strategy. Further treatment options, such as catheter ablation or implantation of a pacemaker and ablation of the atrioventricular (AV) node, are considered once AF recurs. The benefits of first-line ablation in patients presenting with persistent AF have not been tested. Investigators seek to perform a blinded, randomised trial comparing an electrical cardioversion-led strategy with a pulmonary-vein isolation strategy for the treatment of persistent atrial fibrillation. No blinded randomised controlled trial comparing early-ablation strategies to cardioversion-led strategies has been performed. The rationale for blinding where possible in clinical trials is well established. The recently published ORBITA trial performed a blinded, multicentre randomised trial of percutaneous coronary intervention (PCI) in stable angina compared to a placebo procedure. This trial demonstrated that the efficacy of invasive procedures can be assessed with a placebo procedure and that this type of trial remains necessary. Knowledge of treatment assignment influences physician behaviour, drug recommendations and encourages bias in outcome reporting. The treatment effect size and the effects of confounding factors will be exaggerated and thus limit the interpretation of the true patient-experienced outcomes of either strategy. In a comparison of surgical procedures, a sham control arm represents the gold standard of blinding. A systematic review of placebo-controlled surgical trials found no evidence of harm to participants assigned to the placebo group. For a procedure whose primary purpose is to give sustained symptomatic relief, definitive quantification of the true placebo-controlled effect size of AF ablation is necessary. There is a need to clarify the relationship between patient-reported symptoms and the arrhythmia itself. Patient-reported symptoms may not always be related to the severity of the arrhythmia or quality of life. No bias-resistant blinded, randomised, trial has yet been performed seeking to measure the benefits of AF ablation in persistent AF. The investigators of this trial have achieved successful recruitment and concluded the pilot phase (ORBITA AF trial; ClinicalTrials.gov Identifier: NCT03907982) with the goal of assessing feasibility and optimizing the study protocol prior to conducting a larger trial. The positive outcomes of the pilot phase have paved the way for this larger follow-on trial.

Inclusion Criteria:

• Ability to give informed consent
• Age 18-85 years
• Persistent AF (atrial fibrillation lasting > 7days) of total continuous duration <2 years as documented in medical notes.
• Patients being considered for cardioversion.

Exclusion Criteria:

• Creatinine clearance (eGFR) < 30mls/min
• Contraindication or unable to take anticoagulation
• Uncontrolled hypertension
• Contraindication for catheter ablation
• BMI > 40
• Patients in Persistent AF who have had more than one previous cardioversion.
• Established diagnosis of Hypertrophic cardiomyopathy

Patient and physician - blinded randomisation to intervention (DCCV, or Pulmonary Vein Isolation plus DCCV) Once subject participation in the trial is complete, the patient and physician will be unblinded.