Atrial fibrillation (AF) is a heart rhythm disorder associated with debillitating symptoms, psychological distress and heart failure. It can also significantly increase an individuals stroke risk. Catheter ablation (CA) for AF is the most effective way to restore normal heart rhythm. However, AF can recur in up to 50% of patients after their first CA procedure and a second 'top-up' procedure may be needed to maximise effect. Early detection of recurrences can enable planning and treatment and repeat CA procedures.

Post-CA follow-up strategies rely on episodic rhythm monitoring (Holter monitor tests) that usually last between 1 and 7 days. However, AF recurrences can be intermittent and may not occur during these short monitoring episodes. A greater duration of monitoring has been shown to yield greater detection of AF recurrences.

Relying on symptoms alone to detect recurrence is also sub-optimal. AF recurrences can also be insidious. Similar symptoms may be reported from ectopy, atrial tachycardias or atrial flutter. These may require different management approaches, necessitating rhythm characterisation before considering a repeat CA.

The Apple Watch (AW) is a wristwatch that is able to monitor a wearer's heart rate and rhythm regularity as well as facilitating an immediate, real-time single-lead ECG recording. This non-invasive device that can be purchased over- the-counter has demonstrated feasibility in detecting AF and may offer a potential non-invasive, alternative long-term rhythm surveillance strategy to diagnose AF in these patients.

The investigators propose a single-centre, randomised controlled study to compare the standard follow-up strategy after index AF CA versus one supplemented with an AW-led prolonged monitoring strategy to determine if the latter will improve the expediency and rate of AF recurrence detection. Whether this will lead to improved downstream decision-making, reduction in symptomatic events and a lower prevalence of AF in the longer term will also be studied.

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

Participants will be randomised after enrollment to active or control arms of this study