Ischaemic stroke in atrial flutter vs fibrillation: a Finnish nationwide study

doi:10.1093/eurheartj/ehag681

Arrhythmias & electrophysiologyCohort study

Ischaemic stroke in atrial flutter vs fibrillation: a Finnish nationwide study

Eur Heart JPublished 3 Sep 2026

Retrospective cohort study
registry-linkage
nationwide
31 795 (77.6%) initiated anticoagulation during follow-up

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Authors' conclusion

In this large cohort of patients, those with AFL-only had a substantially lower risk of IS than patients with AF-only, suggesting clinically meaningful differences in thromboembolic risk between these arrhythmias.

Study context

Population: Patients with new-onset atrial fibrillation (AF)/atrial flutter (AFL) in Finland, 2007–2018, with electrocardiogram (ECG) documentation
Participants: 40,986 patients · 532,041 ECGs

Exposure: AFL-only and AF & AFL vs AF-only
AF-onlyn = 30,261reference
AFL-onlyn = 2,409
AF & AFLn = 8,316
Outcome: Ischaemic stroke (IS)
Follow-up: Mean 1.2 years

Main finding

As reported in the abstract

Ischaemic stroke

AF & AFL2.1crude rate · 95% CI 1.9–2.2 · per 100 patient-years

AF-only1.9crude rate · 95% CI 1.8–1.9 · per 100 patient-years

AFL-only1.1crude rate · 95% CI 0.9–1.3 · per 100 patient-years

Each group vs AF-onlyAdjusted incidence rate ratio (95% CI)

AFL-only

0.60(0.49–0.74)

AF & AFL

1.11(1.02–1.20)

Ischaemic stroke (IS) overall: 3165 (7.7%)

Observational data: associations, not effects.

Original publication

Ischaemic stroke in atrial flutter vs fibrillation: a Finnish nationwide study. Eur Heart J. Published 3 September 2026. doi:10.1093/eurheartj/ehag681

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Summarised from the published abstract; every number is checked against it