Background:

Different studies with real-life data and randomized controlled trials have shown a detection rate of paroxysmal atrial fibrillation (AF) of 10-20% in patients with cryptogenic stroke using insertable continuous cardiac monitoring for 6 months. More studies are needed, however, to identify factors which can be used to select the patients where the possibility of detecting AF with prolonged rhythm monitoring is highest, to evaluate the best duration of rhythm monitoring, to determine the optimal definition of short-term AF that warrants intervention and to evaluate whether intervention results in improved clinical outcomes.

Methods: The NOR-FIB study is a multi-centre prospective observational trial, designed to evaluate detection of AF in cryptogenic stroke and transient ischemic attack (TIA). Patients admitted with cryptogenic stroke or TIA in stroke units in the Nordic countries, aged 18-80 years are included and have the Reveal LINQ® Insertable cardiac monitor system implanted for 12 months for the purpose of AF detection. Biomarkers that may identify patients, who could derive the most clinical benefit from the detection of AF by prolonged monitoring, are being studied.

Conclusion: This NOR-FIB study will increase our knowledge regarding the occurrence of AF in patients with cryptogenic stroke and TIA that potentially can improve secondary prevention. The study will provide information on biomarkers that may be used to select cryptogenic TIA and stroke patients for long-term monitoring as well as information on the significance of short-term AF and optimal duration of cardiac rhythm monitoring.

Inclusion Criteria:

1. Cryptogenic ischemic stroke patients or symptomatic TIA < 21 days from symptom start.

2. A stroke/TIA is considered to be cryptogenic if no cause can be determined despite an extensive workup according to the standard protocol of the participating center. Before inclusion to the study, the following tests are required as standard tests to establish the diagnosis of cryptogenic stroke or TIA:

   1. Brain MRI or CT†
   2. 12-lead ECG for AF detection
   3. 24-h ECG monitoring for AF detection and premature atrial complex analysis (e.g. Holter)
   4. TEE (transesophageal echocardiography) highly recommended or TTE (transthoracic echocardiography)
   5. Colour Duplex ultrasound examination of the pre-cerebral arteries
   6. CTA or MRA of head and neck to rule out other causes of stroke pathologies

3. Age 18 to 80 at onset of TIA/stroke

4. A participation consent form signed by the patient or a legally authorized representative.

   • TIA cases with acute non-lacunar infarct on Diffusion Weighted Imaging are included as TIA events.

Exclusion Criteria:

1. Known etiology of TIA or stroke.
2. TIA without documented cerebral ischemia on Diffusion Weighed Imaging.
3. Untreated hyperthyroidism
4. Myocardial infarction less than 1 month prior to the stroke or TIA.
5. Coronary bypass grafting less than 1 month prior to the stroke or TIA.
6. Valvular heart disease requiring immediate surgical intervention.
7. History of atrial fibrillation or atrial flutter.
8. Patent Foramen Ovale (PFO) or PFO where there is or was an indication to start oral anticoagulation
9. Permanent indication for OAC treatment at enrollment.
10. Permanent contra-indication for OAC.
11. Life expectancy less than 1 year.
12. Pregnancy
13. An indication for an Implantable Pulse Generator (IPG), Implantable Cardioverter-Defibrillator (ICD), Cardiac Resynchronization Therapy (CRT) or an implantable hemodynamic monitoring system.
14. Patient otherwise not eligible for the study or adherent for follow-up (e.g. non-resident) or has concurrent disease which may affect clinical outcome (e.g. multiple sclerosis, cancer).

Patients admitted to stroke units with cryptogenic ischemic stroke or TIA

Plan to share IPD