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Completed

NCT Number: NCT05007847

Improving AF Detection in Cryptogenic Stroke

No cause for stroke is found in up to 30% of cases despite extensive investigations. These are called cryptogenic strokes (CS). 1 in 4 stroke survivors will suffer another in 5 years and this is a leading cause of fear and anxiety. A common reason for CS is an undetected heart rhythm disorder called atrial fibrillation (AF). AF occurs intermittently, so it may not be detected during the mandated 24-96 hours of rhythm monitoring that is performed as part of the standard post-stroke investigation strategy.

A randomised controlled study in 2014 showed that whereas this standard monitoring strategy picks up AF in 2% of CS patients, longer-term, continuous monitoring for 12 months can pick up AF in 13% of patients. This suggests the standard strategy may miss AF in a proportion of CS patients and thus also the opportunity to mitigate against further strokes with anticoagulation therapy. Prolonged monitoring has traditionally required a minimally-invasive surgical procedure to implant a recording device under the skin at a specialist centre. A specifically trained team is also required to interpret the large number of recordings this strategy yields.

The Apple Watch (AW) is a wristwatch able to monitor a wearer's heart rate and rhythm regularity and facilitates real- time, single-lead ECG recordings. This over-the-counter, non-invasive device has demonstrated feasibility and has a Certification (CE) Mark for detecting AF. It may offer a potential non-invasive alternative long-term rhythm surveillance strategy to diagnose AF in these patients.

The investigators propose a study in which CS patients will be randomised in a 1:1 ratio to receive additional AW monitoring on top of standard care versus standard care alone. The investigators shall then explore the incidence of AF in the two groups at 1 year and how it impacts clinical outcomes too.

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Key information

Conditions

Cryptogenic Stroke Arrhythmias, Cardiac Atrial Fibrillation Brain Diseases Cardiovascular Diseases Central Nervous System Diseases Cerebrovascular Disorders Heart Diseases Ischemic Stroke Nervous System Diseases Pathologic Processes Pathological Conditions, Signs and Symptoms Stroke Vascular Diseases

Age range

30 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

St Bartholomew's Hospital, City of London, London, United Kingdom

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Recent stroke or TIA event (<90 days) that is supported by consistency between symptoms and findings on brain magnetic resonance imaging (MRI) or computed tomography (CT). Patients with TIA will be enrolled only if symptoms at presentation were speech problems, limb weakness, or hemianopsia. Diagnosis shall be made by a Consultant Stroke physician.
  • Stroke classified as cryptogenic following extensive investigations to rule out a cause as per local protocol, but to include at least:
  • Trans-thoracic echocardiogram
  • A period of at least 24-hour rhythm monitoring with no evidence of AF.
  • MRI or CT-angiography of the brain
  • Sufficient mobility and dexterity to perform an ECG recording on the AW by touching the dial on the watch when worn with the contralateral hand for 30 seconds.
  • 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 to participate in the study.

Exclusion criteria

  • Documented history of AF or atrial flutter.
  • Expected to undergo heart surgery in the 1 year following the stroke event.
  • Any episode of myocardial infarction, coronary intervention or coronary artery bypass grafting <1 month prior to the stroke event
  • Any other indication for oral anti-coagulation.
  • Patient has a cardiac implantable electronic device in-situ already or is expected to undergo implantation in the 1 year following the stroke event (excluding implantable loop recorder for the investigation of the CS).
  • Previous left atrial (LA) ablation or LA surgery
  • Life expectancy less than 1 year

Treatment and study plan

Apple Watch-based heart rhythm monitoring

Device

For the duration of the study, participants in the active arm will be asked to make ECG recordings in three circumstances:

Routinely once per day from the day of randomisation till the 12-month visit after AF Catheter Ablation (they will be encouraged to do so at the same time each day with the option to set a reminder on the watch).

If the AW requests them to do so (the automatic AF-notification algorithm will be active throughout the study period and if AF is suspected based on the tachogram, it will trigger notification for the participant to make an ECG recording). This will be till the 12-month time point.

If the patient has symptoms of palpitations, pre-syncope or syncope. This will be till the 12-month time point. Monitoring should continue even if AF has been diagnosed to characterise arrhythmia burden and profile. Participants will be given the contact details of a dedicated email inbox to which to send ECGs recorded through the AW.

Primary outcomes

  1. Atrial fibrillation detection rate

    Time frame: 12 months

Secondary outcomes

  1. Incidence of non-elective, hospital admissions.

    Time frame: 12 months

  2. Incidence of recurrent stroke or TIA.

    Time frame: 12 months

Other outcomes

  1. Exploratory study of correlation between participant activity and AF

    Time frame: 12 months

    Accelerometer, activity and heart rate data [Active arm only]

Sponsors and collaborators

Lead sponsor

Barts & The London NHS Trust

Other

Registry information

Official study title

A Non-invasive, Prolonged Surveillance Strategy Using Apple Watch for Atrial Fibrillation Detection in Cryptogenic Stroke

Acronym: CSAF-AW

Important dates

Study start
2022
Primary completion
2025
Study completion
2025
First posted
Aug 16, 2021
Registry last updated
Mar 25, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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