Arrhythmias & electrophysiology

Stroke and bleeding risk in atrial fibrillation with CHA2DS2-VASC risk score of one: the Norwegian AFNOR study

Eur Heart JPublished Nationwide cohort study

An erratum to this article was published (Eur Heart J, 8 Sep 2025 ↗)

Main finding · Ischaemic stroke (AF patients)Result — go to the resultAdjusted hazard ratio 0.47 95% CI 0.37–0.59

Authors' conclusion

In AF patients at intermediate risk of stroke, OAC use was associated with overall favourable clinical outcomes. Non-anticoagulated AF patients had higher risk of ischaemic stroke compared to the general population without AF with the same risk profile.

Study context

Population
Individuals with non-sex CHA2DS2-VASc score of one, Norway, 2011–1834,460 atrial fibrillation (AF) patients
Participants
1,118,762 individuals
Exposure
Oral anticoagulant (OAC) users vs non-users; non-anticoagulated AF vs non-AF
Outcome
Ischaemic stroke and bleeding risk in AF with and without OAC
Follow-up
One-year IR
Methodological detailsNorwegian
  • Norwegian

Main finding

Ischaemic stroke (AF patients)

Adjusted hazard ratio

0.47

95% CI 0.37–0.59

By group

OAC users

0.51%/py

Non-users

1.05%/py

OAC usersvs Non-users
aHR 0.47 (95% CI 0.37–0.59)

As reported in the abstract

Observational data: associations, not effects.

Further findings

Combined ischaemic stroke, major bleeding and mortality

OAC use associated with lower risk of the combined outcome, aHR
0.57 [0.51-0.63] (95% CI)

Ischaemic stroke, non-anticoagulated AF vs non-AF individuals with the same risk profile

Higher risk of ischaemic stroke in non-anticoagulated AF vs non-AF individuals, aHR
2.47 [2.17-2.81] (95% CI)

Safety

OutcomeOAC usersNon-usersaHR (95% CI)
Intracranial haemorrhage · 1 yearOAC usersvs Non-usersIR 0.28%/pyIR 0.19%/py1.23 (0.88–1.72)

Major bleeding

OAC use associated with increased risk of major bleeding, aHR
1.37 [1.16-1.63] (95% CI)

Original publication

Stroke and bleeding risk in atrial fibrillation with CHA2DS2-VASC risk score of one: the Norwegian AFNOR study. Eur Heart J. Published 23 November 2023. doi:10.1093/eurheartj/ehad659

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