Cryptogenic StrokeCSAF-AWNCT05007847
Improving AF Detection in Cryptogenic Stroke
A study testing Apple Watch-based heart rhythm monitoring in people with Cryptogenic Stroke and Atrial Fibrillation, run by Barts & The London NHS Trust at 4 sites in United Kingdom.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 30 years and older
- Conditions the study is for
- Cryptogenic Stroke, Atrial Fibrillation
- What is being tested?
- Apple Watch-based heart rhythm monitoring
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 27 participants
- Where
- 4 sitesUnited Kingdom
- Study dates
- 4 Feb 2022to 28 Feb 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 30 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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.
Who cannot join
- 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
Trial locations and contacts
4 sites in 1 country.
United Kingdom4 sites
St Bartholomew's Hospital
City of London, London, EC1A7BE
Whipps Cross University Hospital
London, UK, E11 1NR
Royal London Hospital
London, E1 1FR
The National Hospital for Neurology and Neurosurgery
London, WC1N 3BG
About this study
Official title: A Non-invasive, Prolonged Surveillance Strategy Using Apple Watch for Atrial Fibrillation 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.
Read more
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.
- Conditions
- Cryptogenic Stroke, Atrial Fibrillation
- Being tested
- Apple Watch-based heart rhythm monitoring
- Keywords
- cryptogenic stroke, atrial fibrillation, wearable
- Medical subject headings
- Ischemic Stroke, Atrial Fibrillation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Apple Watch-based heart rhythm monitoringDevice
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.
| Study group | Role | What they receive |
|---|---|---|
| Active | Active comparator | Participants randomised to the active arm will be provided with an AW Series 4 on Day 0 for the duration of the study. They shall undergo an education and training session to ensure technical competency of heart rhythm recording and familiarity with the recommended recording schedule for the duration of the study. Participants will also be given the contact details for a dedicated email mailbox for the duration of the study through which they can submit remote transmissions of ECG data. Receives: Device: Apple Watch-based heart rhythm monitoring |
| Control | No intervention | Participants in the control arm will be advised to continue with the standard of care and advised to contact their direct clinical team or primary care physician should they experience any symptoms of concern (palpitations, dizziness, collapse). They will be contacted by the study team at 6 and 12 months for clinical assessment (symptoms, hospitalisation data, further stroke events, mortality). |
What is being measured
The primary outcome is the main question the study is designed to answer.
Atrial fibrillation detection rate
Measured: 12 months
Secondary outcomes (2)
Incidence of non-elective, hospital admissions.
Measured: 12 months
Incidence of recurrent stroke or TIA.
Measured: 12 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 Aug 2021
- Study start4 Feb 2022
- Primary completion28 Feb 2025
- Study completion28 Feb 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Cryptogenic StrokeStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Diagnosis
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- The investigators propose a prospective, randomised controlled study to determine our hypothesis. This single-centre, investigator-initiated trial will be performed at Barts Health NHS Trust which provides tertiary cardiac electrophysiology services to 4 stroke units part of the London Stroke Care Network (SCN). Participants will be randomised on day 0 to either the active or control study arm. Participants randomised to the active arm will be provided with an AW Series 4 on Day 0 for the duration of the study. All participants will be followed up for 12 months after enrolment.
- Masking
- None (open label)
- Enrolment
- 27 participants (actual)
Sponsor and investigators
- Lead sponsor
- Barts & The London NHS Trust
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Richard Schilling, Principal investigator, Barts & The London NHS Trust
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05007847
- Sponsor's protocol ID
- 284826
- Acronym
- CSAF-AW
- Status last verified
- Mar 2025
- First submitted
- 14 Jul 2021
- Last updated
- 25 Mar 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 25 Mar 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Non-invasive, Prolonged Surveillance Strategy Using Apple Watch for Atrial Fibrillation Detection in Cryptogenic Stroke
- ClinicalTrials.gov ID
- NCT05007847
- Acronym / sponsor ID
- CSAF-AW / 284826
- Conditions
- Cryptogenic Stroke, Atrial Fibrillation
- Keywords
- cryptogenic stroke, atrial fibrillation, wearable
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 27 participants (actual)
- Lead sponsor
- Barts & The London NHS TrustUniversity, hospital or other
- Study start
- 4 Feb 2022 (actual)
- Primary completion
- 28 Feb 2025 (actual)
- Study completion
- 28 Feb 2025 (actual)
- First posted
- 16 Aug 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- The investigators propose a prospective, randomised controlled study to determine our hypothesis. This single-centre, investigator-initiated trial will be performed at Barts Health NHS Trust which provides tertiary cardiac electrophysiology services to 4 stroke units part of the London Stroke Care Network (SCN). Participants will be randomised on day 0 to either the active or control study arm. Participants randomised to the active arm will be provided with an AW Series 4 on Day 0 for the duration of the study. All participants will be followed up for 12 months after enrolment.
| Arm | Type | Receives |
|---|---|---|
| Active | Active comparator | Device: Apple Watch-based heart rhythm monitoringParticipants randomised to the active arm will be provided with an AW Series 4 on Day 0 for the duration of the study. They shall undergo an education and training session to ensure technical competency of heart rhythm recording and familiarity with the recommended recording schedule for the duration of the study. Participants will also be given the contact details for a dedicated email mailbox for the duration of the study through which they can submit remote transmissions of ECG data. |
| Control | No intervention | –Participants in the control arm will be advised to continue with the standard of care and advised to contact their direct clinical team or primary care physician should they experience any symptoms of concern (palpitations, dizziness, collapse). They will be contacted by the study team at 6 and 12 months for clinical assessment (symptoms, hospitalisation data, further stroke events, mortality). |
Who may qualify
- Ages
- 30 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (8 listed)
- 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:
- 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.
Key exclusion criteria (7 listed)
- 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).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Apple Watch-based heart rhythm monitoringFor 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. | Device | Active |
Primary outcome
Atrial fibrillation detection rate
Time frame: 12 months
2 secondary outcomes
Incidence of non-elective, hospital admissions.
Time frame: 12 months
Incidence of recurrent stroke or TIA.
Time frame: 12 months
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 25 Mar 2025.
- Individual participant dataSharing planned: No
Related trials for Cryptogenic Stroke
RecruitingPhase 4
NeuroAiD Patient-Reported Outcomes in Patients With Mild to Moderate Ischemic Stroke
Stroke, Stroke, Acute Ischemic
Recruiting
Intensive Cancer Screening After Cryptogenic Stroke
Occult Cancer
Recruiting
Comparing Two PFO Closure Devices in Adults With Previous Stroke or TIA
Patent Foramen Ovale, Stroke
Active, not recruitingPhase 3
Assessment of Flecainide to Lower the Patent Foramen Ovale Closure Risk of Atrial Arrhythmia or Tachycardia
Patent Foramen Ovale, Atrial Arrhythmia
Recruiting
Early Feasibility Study (EFS) Evaluating Percutaneous Repair of the Atrial Septum With a Novel PFO Occluder: The PROTEA-PFO Study
PFO, PFO - Patent Foramen Ovale
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Richard Schilling principal investigator
Barts & The London NHS Trust
4 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Apple Watch-based heart rhythm monitoring in people with Cryptogenic Stroke and Atrial Fibrillation, run by Barts & The London NHS Trust at 4 sites in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 8 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 25 Mar 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 sites in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Atrial fibrillation detection rate (time frame: 12 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 25 Mar 2025.