In order to bring you the best possible user experience, this site uses Javascript. If you are seeing this message, it is likely that the Javascript option in your browser is disabled. For optimal viewing of this site, please ensure that Javascript is enabled for your browser.
Did you know that your browser is out of date? To get the best experience using our website we recommend that you upgrade to a newer version. Learn more.

How to prevent recurrent stroke when the cause is unknown

Atrial Fibrillation
Risk Factors and Prevention

Copenhagen, Denmark – 4 April 2022:  Nearly one-third of patients with a stroke of unknown cause have a heart rhythm disorder that can be treated to prevent another stroke. That’s the finding of the NOR-FIB study presented at EHRA 2022, a scientific congress of the European Society of Cardiology (ESC).1

In the study, stroke patients had their heart rhythm monitored for 12 months with a tiny implanted device. “More than 90% of stroke patients found to have atrial fibrillation had no symptoms of the heart rhythm disorder,” said study author Dr. Barbara Ratajczak-Tretel of Østfold Hospital Trust, Sarpsborg, Norway. “For many patients, atrial fibrillation would have gone undiagnosed and untreated without the continuous monitoring, putting them at risk of another stroke.”

Most strokes are ischaemic, meaning a blockage stops blood flow to the brain. In approximately one in four ischaemic strokes the cause is undetermined. “The best therapy to prevent another stroke depends on the underlying cause,” said Dr. Ratajczak-Tretel. “Those with atrial fibrillation should receive oral anticoagulants but a definitive diagnosis is needed before these drugs can be prescribed. Atrial fibrillation can be transient and asymptomatic making it difficult to detect.”

The Nordic Atrial Fibrillation and Stroke (NOR-FIB) study examined the ability of continuous heart rhythm monitoring for one year with an implanted device to identify atrial fibrillation in patients with an ischaemic stroke or mini-stroke (transient ischaemic attack; TIA) of unknown aetiology.

The prospective, observational study included 259 patients with no documented history of atrial fibrillation from 18 centres in Norway, Denmark and Sweden. All patients received a cardiac monitor, which was implanted a median of nine days after the stroke or TIA. The device is one-third the size of a AAA battery and was inserted subcutaneously over the heart under local anaesthesia.

Data from the device were transmitted automatically through a secure network to a core lab of two neurologists and two cardiologists and evaluated once a week. When atrial fibrillation lasting at least two minutes was detected, the core lab contacted the patient’s physician who then prescribed oral anticoagulants. Patients were followed up for 12 months.

During the 12-month monitoring period, 74 patients (29%) were diagnosed with atrial fibrillation, of whom 93% were asymptomatic. Oral anticoagulation was recommended for all patients with atrial fibrillation and at 12 months, 72 of 74 patients (97%) were on this therapy.

In the course of follow-up, two strokes occurred in the atrial fibrillation group (both before the first atrial fibrillation episode was detected and anticoagulation initiated) and nine in patients without atrial fibrillation, however the difference was not statistically significant.

Device complications were experienced by three patients (1.2%). One patient had an infection at the implantation site and the device had to be removed. One patient had a skin tear and the device had to be moved to another position. The third patient developed a subcutaneous haematoma (bruising).

Dr. Ratajczak-Tretel said: “In this study, we found that an implantable cardiac monitor was effective for diagnosing underlying atrial fibrillation, which was identified in 29% of patients with a stroke or TIA of indeterminate cause. As the probable cause of the stroke or TIA was detected, these patients were able to start oral anticoagulation. Atrial fibrillation was asymptomatic in most cases and may not have been detected or treated without continuous monitoring.”



Notes to editor

ESC Press Office
Tel: +33 (0) 7 8531 2036

Follow us on Twitter @ESCardioNews 


Funding: NOR-FIB is an investigator driven academic study. Barbara Ratajczak-Tretel and Anna Tancin Lambert are recipients of PhD grants from the South-Eastern Norway Regional Health Authority. The NOR-FIB Study was supported by Oslo University Hospital, Norwegian Health Association, South-Eastern Norway Regional Health Authority, Østfold Hospital Trust and the research infrastructure of the European Cerebrovascular Research Infrastructure (ECRI). Devices were partly made available by Medtronic.


Disclosures: Dan Atar has received honoraria from Actelion, Amgen, AstraZeneca, BMS/Pfizer, Bayer, Boehringer-Ingelheim, MSD, Novartis, Roche Diagnostics, Sanofi and Vifor Pharma. Dan Atar has received research grants to the institution from BMS/Pfizer, Bayer, Roche Diagnostics and Medtronic (support with devices for this study). Anne Hege Aamodt has received travel support, honoraria for advice or lecturing from Bayer, Boehringer Ingelheim, BMS, Allergan, Teva, Sanofi-Genzyme, Novartis, Roche, and Teva and research grant from Boehringer Ingelheim outside this project. Barbara Ratajczak-Tretel and Anna Tancin Lambert have received travel funding from Medtronic.


References and notes

1The abstract “Detection of atrial fibrillation in patients with cryptogenic stroke: The Nordic Atrial Fibrillation and Stroke (NOR-FIB) study - topline results” will be presented during the session “What is new on stroke prevention” which takes place on 4 April at 13:10 CEST in Room 2.


About the European Heart Rhythm Association

The European Heart Rhythm Association (EHRA) is a branch of the European Society of Cardiology (ESC). Its aim is to improve patients’ quality of life and reduce sudden cardiac death by limiting the impact of heart rhythm disturbances. 


About the EHRA Congress  #EHRA2022

EHRA 2022 is the annual congress of the European Heart Rhythm Association (EHRA) of the European Society of Cardiology (ESC).


About the European Society of Cardiology

The ESC brings together health care professionals from more than 150 countries, working to advance cardiovascular medicine and help people to live longer, healthier lives.


Information for journalists about registration for EHRA 2022

EHRA 2022 takes 3 to 5 April at the Bella Center in Copenhagen, Denmark and online. Explore the scientific programme.

  • Free registration applies to accredited press.
  • Credentials: A valid press card or appropriate letter of assignment with proof of three recent published articles. Read the ESC media and embargo policy.
  • The ESC Press Office will verify the documents and confirm by email that your press accreditation is valid.
  • The ESC Press Office decision is final regarding all press registration requests.