What is the clinical evidence from this study?

Study design: Cohort. Population: Atrial fibrillation (n=174094). Intervention: Oral anticoagulation non-use vs. Oral anticoagulation use. Primary outcome: Factors associated with non-use of oral anticoagulation at first ischemic stroke (CHA2DS2-VA score of 0 points) (OR 4.561, 95% CI 3.097-6.718).

June 20, 2025Open Access

Factors associated with oral anticoagulant non-use at first ischemic stroke in atrial fibrillation: A nationwide study

MVMarko VilpponenUniversity of Helsinki AAAapo L. AroElectrophysiology OHOlli HalminenElectrophysiology

Key Result

A CHA2DS2-VA score of 0 points was the strongest factor associated with oral anticoagulant non-use at the time of first ischemic stroke in patients with atrial fibrillation (OR 4.561).

Study Design

Type

Cohort (n=174,094)

Multicenter

Yes

Structured PICO

What factors are associated with the non-use of oral anticoagulation at the time of first-ever ischemic stroke in patients with atrial fibrillation?

Population

174,094 adult patients with new-onset atrial fibrillation (AF) in Finland between 2007 and 2017, without prior ischemic stroke or transient ischemic attack (TIA). The cohort included 11,680 patients who experienced a first-ever ischemic stroke (mean age 79.0 years, 56.9% female) and 157,376 who did not (mean age 71.2 years, 48.6% female).

Intervention

Oral anticoagulation (OAC) therapy (warfarin or direct oral anticoagulants including apixaban, rivaroxaban, dabigatran, and edoxaban)

Comparator

Non-use of oral anticoagulation therapy

Outcome

Factors associated with non-use of oral anticoagulation at the time of first-ever ischemic stroke

A significant majority of atrial fibrillation patients experiencing their first ischemic stroke are not on oral anticoagulation, often driven by perceived low risk (CHA2DS2-VA score 0) or specific comorbidities like alcohol abuse and dementia.

Main Result

Effect estimate: OR 4.561 (95% CI 3.097-6.718)

Limitations

Information bias inherent to administrative registry data
Lack of information on different subtypes of atrial fibrillation and precise etiology of ischemic stroke
Inability to establish a direct causal relationship between lack of anticoagulation and ischemic stroke
Medication purchase data does not confirm actual patient adherence to the prescribed treatment
Unmeasured confounding due to lack of data on lifestyle factors such as smoking, physical activity, obesity, and nutrition

Abstract

Background: Limited data exist on characteristics and patterns associated with patients with atrial fibrillation (AF) who encounter first-ever ischemic stroke (IS) while not on oral anticoagulation (OAC) therapy. Methods: From a nationwide registry-linkage database including all patients with AF in Finland from 2007 to 2017, we included those with IS after diagnosis of AF and those without IS. Factors associated with non-OAC use among IS patients were examined using logistic regression, with separate models for independent variables and risk scores. Results: Among 174,094 patients with new-onset AF, 11,680 (6.7%) patients (56.9% female; mean age 79.0 years) experienced IS. A total of 7507 (64.3%) of IS patients were not on OAC at the time of IS (mean age 78.9 years; 57.2% female). The proportion of non-OAC decreased from 77.2% to 45.6% over the study period. In the adjusted logistic regression model, the strongest factor associated with non-OAC was CHA 2 DS 2 -VA score of 0 points (OR 4.561; 95% CI, 3.097–6.718), followed by a score of 1 point (OR 2.382; 95% CI, 1.971–2.879). Other significant independent factors associated with non-OAC use were alcohol abuse (OR 2.282; 95% CI, 1.805–2.885), liver dysfunction (OR 2.120; 95% CI, 1.335–3.367), renal dysfunction (OR 1.430; 95% CI, 1.200–1.703), dementia (OR 1.394; 95% CI, 1.227–1.583), prior myocardial infarction (OR 1.346; 95% CI, 1.181–1.535), age <65 years (OR 1.274; 95% CI, 1.034–1.571), lowest income (OR 1.232; 95% CI, 1.104–1.374), female sex (OR 1.177; 95% CI, 1.077–1.287), and antiplatelets/NSAID use (OR 1.133; 95% CI, 1.042–1.231). Conclusions: Less than 2% of AF patients experienced IS during study period and among these around 63% were without appropriate OAC therapy at the time of the IS. However, decreasing trend of non-OAC use was identified throughout the study period.

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