Detection of atrial fibrillation in patients with cryptogenic stroke: The Nordic Atrial Fibrillation and Stroke (NOR-FIB) study - topline results

Abstract

Funding Acknowledgements Type of funding sources: Other. Main funding source(s): NOR-FIB is an investigator driven academic study. 100 of 259 devices are supported by Medtronic. BRT and ATL are recipients of a PhD grants from the South-Eastern Norway Regional Health Authority. The study is supported by the research infrastructure of the European Cerebrovascular Research Infrastructure (ECRI). Background Cardioembolism due to occult atrial fibrillation (AF) is one of the common causes often identified by additional investigations in patients with cryptogenic stroke (CS). A large proportion of recurrent cerebral infarctions caused by AF can probably be prevented if more patients receive optimal cardiac monitoring after CS and TIA. Purpose The aim of the prospective observational multi-center NOR-FIB study was to detect and quantify AF in patients with cryptogenic stroke or TIA under continuous 12 months cardiac rhythm monitoring with an implantable cardiac monitor (ICM) and to possibly identify biomarkers predicting incident AF. Methods Patients with cryptogenic stroke and TIA diagnosed after state-of-the-art work-up had their ICM implanted by a stroke physician within 14 days after symptom onset. All patients were followed clinically and by rhythm monitoring for 12 months. AF was defined by detected atrial arrhythmia episodes ≥ 2 min, and these patients were considered for a change of their secondary prevention from antiplatelet drugs to oral anticoagulants (OAC). Results A total of 259 patients with cryptogenic stroke or TIA from 18 hospitals in Norway, Sweden and Denmark were included. After 12 months follow-up 74 (28.6 %) patients were diagnosed with paroxysmal AF, of which 91.9% were asymptomatic. Patients with AF had significantly higher mean age (72.6 vs 62.2, p<0.001), more severe stroke (median National Institute Stroke Scale Score on admission 2 vs 1, p 0.002) and higher pre-stroke median CHA2DS2-VASc score (3 vs 2, p<0.001) than patients without AF. Both hypertension and hyperlipidemia was more common in patients with AF. In 64 (86.5%) cases AF was detected early after index stroke, i.e., within the first two months of monitoring (mean 47.7 days + 52,1). Recurrent AF episodes were detected in 68 (91.9%) cases. Of the 74 AF patients, 72 (97.3%) were switched to OAC. Recurrent strokes during follow-up occurred in 2 AF patients (2.7 %) and in 9 non-AF patients (4.9 %). Conclusion AF was detected in 29% of all cryptogenic stroke/TIA patients. Most of the patients were asymptomatic for their arrhythmia, and would have gone undiagnosed without a continuous monitoring approach. Since most of the patients with detected AF were switched to OAC, the 12 months risk of recurrent stroke in this group was low. Prolonged cardiac rhythm monitoring with ICMs is an effective tool for diagnosing underlying asymptomatic AF in a patient population typically confined to a stroke unit.

Detection of atrial fibrillation in real world setting in patients with cryptogenic stroke and an implantable loop recorder

“…Another novel finding in our study is the high incidence of recurrent strokes occurring in patients without ILR detected arrhythmia ( n = 27, 87.1% of total recurrent strokes). Previous European studies have reported variable rates of recurrent stroke following CS in the absence of ILR detected AF, ranging from around 50%–80% 14,15 . The higher proportion of recurrent strokes in our study may partly be accounted for by the high proportion of African American patients.…”

“…Previous European studies have reported variable rates of recurrent stroke following CS in the absence of ILR detected AF, ranging from around 50%-80%. 14,15 The higher proportion of recurrent strokes in our study may partly be accounted for by the high proportion of African American patients.…”

Detection of Atrial Fibrillation in Real World Setting in Patients with Cryptogenic Stroke and an Implantable Loop Recorder

“…Another novel nding in our study is the high incidence of recurrent strokes occurring in patients without ILR detected arrhythmia (n = 27, 87.1% of total recurrent strokes). Previous European studies have reported variable rates of recurrent stroke following CS in the absence of ILR detected AF, ranging from around 50-80% [14,15]. The higher proportion of recurrent strokes occurring in the absence of detected AF in the current study may also partly be accounted for by the high proportion of African American patients.…”

Performance of Different Risk Scores for the Detection of Atrial Fibrillation Among Patients With Cryptogenic Stroke

“…To the best of our knowledge, there is only 1 available study in the literature evaluating different risk scores for AF prediction in a Norwegian cohort of patients with CS. 43 This study evaluated 8 clinical risk scores in 259 patients with CS or cryptogenic transient ischemic attack. The results of this study are not directly comparable to our findings, given differences in score selection (C 2 HEST score was not evaluated in the Norwegian study), patient selection (patients with transient ischemic attack were not included in our study), and duration of ICM [≤12 months in the Norwegian study and median duration of 16 months (IQR, 8–25) in our study].…”