Embolic Stroke of Undetermined Source and Detection of Atrial Fibrillation on Follow-Up: How Much Causality Is There?
BACKGROUND
There is increasing debate whether atrial fibrillation (AF) episodes during follow-up in patients with embolic stroke of undetermined source (ESUS) are causally associated with the event. AF-related strokes are more severe than strokes of other etiologies. In this context, we aimed to compare stroke severity between ESUS patients diagnosed with AF during follow-up and those who were not. We hypothesized that, if AF episodes detected during follow-up are indeed causally associated with the index event, stroke severity in the AF group should be higher than the non-AF group.


METHODS
Dataset was derived from the Athens Stroke Registry. ESUS was defined by the Cryptogenic Stroke/ESUS International-Working-Group criteria. Stroke severity was assessed by the National Institutes of Health Stroke Scale (NIHSS) score. Cumulative probabilities of recurrent stroke or peripheral embolism in the AF and non-AF ESUS groups were estimated by Kaplan-Meier analyses.


RESULTS
Among 275 ESUS patients, AF was detected during follow-up in 80 (29.1%), either during repeated electrocardiogram monitoring (18.2%) or during hospitalization for stroke recurrence (10.9%). NIHSS score was similar between the two groups (5 [2-13] versus 5 [2-14], P = .998). More recurrent strokes or peripheral embolisms occurred in the AF group compared with the non-AF group (42.5% versus 13.3%, P = .001).


CONCLUSIONS
Stroke severity is similar between ESUS patients who were diagnosed with AF during follow-up and those who were not. Given that AF-related strokes are more severe than strokes of other etiologies, this finding challenges the assumption that the association between ESUS and AF detected during follow-up is as frequently causal as regarded.
Department of Medicine, Larissa University Hospital, School of Medicine, University of Thessaly, Larissa, Greece. Electronic address: gntaios@med.uth.gr.
George
G
Ntaios
Department of Medicine, Larissa University Hospital, School of Medicine, University of Thessaly, Larissa, Greece; Stroke Service, Department of Neurosciences, Leeds Teaching Hospitals NHS Trust and Medical School, University of Leeds, Leeds, UK.
Vasileios
V
Papavasileiou
University of Birmingham Institute of Cardiovascular Sciences, City Hospital, Birmingham, UK.
Gregory Y H
GY
Lip
Department of Medicine, Ioannina University Hospital, School of Medicine, University of Ioannina, Ioannina, Greece.
Haralampos
H
Milionis
Department of Medicine, Larissa University Hospital, School of Medicine, University of Thessaly, Larissa, Greece.
Konstantinos
K
Makaritsis
Department of Clinical Therapeutics, Medical School of Athens, Alexandra Hospital, Athens, Greece.
Anastasia
A
Vemmou
Department of Clinical Therapeutics, Medical School of Athens, Alexandra Hospital, Athens, Greece.
Eleni
E
Koroboki
Department of Clinical Therapeutics, Medical School of Athens, Alexandra Hospital, Athens, Greece.
Efstathios
E
Manios
Department of Neurology, Eginition Hospital, University of Athens Medical School, Athens, Greece.
Konstantinos
K
Spengos
Neurology Service, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland.
Patrik
P
Michel
Department of Clinical Therapeutics, Medical School of Athens, Alexandra Hospital, Athens, Greece.
Konstantinos
K
Vemmos
D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000453:epidemiology*; D004185:Disability Evaluation; D004562:Electrocardiography; D005260:Female; D006115:Greece / Q000453:epidemiology; D006801:Humans; D020766:Intracranial Embolism / Q000175:diagnosis / Q000453:epidemiology*; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D012008:Recurrence; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D020521:Stroke / Q000175:diagnosis / Q000453:epidemiology*; D013997:Time Factors
Stroke; atrial fibrillation; embolism; stroke severity