Inclusion Criteria:  Referred for first AFCA procedure by a Consultant electrophysiologist. Paroxysmal or persistent AF captured on ECG but not in continuous AF for more than 3 years. (Paroxysmal AF is defined as an episode of AF that terminates spontaneously or with intervention within 7 days of onset. Persistent AF will be defined as any continuous episode lasting longer than 7 days or requiring intervention to restore sinus rhythm after this time.) At least one episode of AF must have been documented by ECG or Holter within 12 months of inclusion in the study. Continuous anticoagulation with warfarin (INR 2-3), low molecular weight heparin, or a novel oral anticoagulant (dabigatran, apixaban, rivaroxaban, edoxaban) for ≥4 weeks prior to the ablation; or a TEE that excludes LA thrombus ≤48 hours before ablation. Access to a smartphone with Apple-operating system (OS) within their household for syncing with their watch. Participants must be able and willing to provide written informed consent  Exclusion Criteria:  Patients with permanent AF. Permanent AF is defined as chronic, persisting AF (typically more than 1 year) for which cardioversion (pharmacologic or electrical) has failed or will never be attempted. Patients with AF felt to be secondary to an obvious reversible cause. Patients who are, or may potentially be pregnant. Any cardiac implantable electronic device in situ or expected to undergo implantation in the next 12 months. Previous left atrial (LA) ablation or LA surgery Pre-existing pulmonary vein stenosis or PV stent Pre-existing hemi-diaphragmatic paralysis Contraindication to anticoagulation or radiocontrast materials Acute coronary syndrome within 4 weeks as defined by ECG ST segment depression or prominent T-wave inversion and/or positive biomarkers of necrosis (e.g. troponin) in the absence of ST-segment elevation and in an appropriate clinical setting (chest discomfort or angina equivalent). Cardiac surgery, angioplasty, or cerebrovascular accident within 4 weeks prior to enrolment. Life expectancy less than 1 year