Key result
Untreated new-onset AF linked to ~2.5-fold higher 1-year rate of ischaemic stroke than ICH.
Why the study?
After the introduction of DOACs improved oral anticoagulation coverage in AF, the risks of ischaemic stroke and intracranial haemorrhage among remaining non-anticoagulated patients in large DOAC-era cohorts have seldom been reported.
Cohort (n=41,076)
Yes
In non-anticoagulated patients with new-onset atrial fibrillation during the DOAC era, the one-year incidence rate of ischaemic stroke is 2.5-fold higher than that of intracranial haemorrhage, with both risks rising alongside higher CHA2DS2-VA scores.
Contemporary untreated AF stroke/ICH rates rise with CHA2DS2-VA; supports score-based stratification but leaves optimal OAC thresholds open.
Background and aims After introduction of direct oral anticoagulants (DOACs) the coverage of oral anticoagulation (OAC) therapy in patients with atrial fibrillation (AF) has improved, leaving a smaller proportion of patients with new-onset AF without anticoagulation. The risk of ischaemic stroke (IS) and intracranial haemorrhage (ICH) of non-anticoagulated patients in large DOAC era cohorts are seldom reported. We analysed the one-year nationwide incidence of IS and ICH in non-anticoagulated patients with new-onset AF. Methods The Finnish AntiCoagulation in Atrial Fibrillation (FinACAF) - study is nationwide retrospective register-based linkage study which covers all patients with AF in Finland between years 2004 and 2018 at all levels of care. Patients with new-onset AF in years 2011-2017 without OAC therapy initiation within a year of AF diagnosis were analysed for one-year incidences of IS and ICH. Patients with prior OAC use or date of death within 90-days of cohort entry were excluded from the analysis. Non-anticoagulated patients were assigned to groups according to their CHA2DS2-VA -scores, and cumulative incidences with death as a competing risk were plotted for IS and ICH. Results Out of 141 399 patients with new-onset AF, 41 076 patients (mean age 68.1 years, mean CHA2DS2VA-score of 2.4) were non-anticoagulated and eligible for outcome analysis. In one-year follow-up a total of 883 IS events were recorded with IS incidence of 2.26/100 patient years (py) (Table 1). The respective rates of IS in CHA2DS2VA -groups were 0.21/100 py for CHA2DS2VA 0p, 0.52/100 py for CHA2DS2VA 1p, 1.35/100 py for CHA2DS2VA 2p, 3.41/100 py for CHA2DS2VA 3p, 4.39/100 py for CHA2DS2VA 4p, and 5.61/100 py for CHA2DS2VA >4p. Similarly, 344 ICH events were recorded overall with ICH rate of 0.88/100 py in the cohort. The respective rates of ICH in CHA2DS2VA -categories were 0.26/100 py for CHA2DS2VA 0p, 0.34/100 py for CHA2DS2VA 1p, 0.86/100 py for CHA2DS2VA 2p, 1.27/100 py CHA2DS2VA 3p, 1.35/100 py for CHA2DS2VA 4p, and 1.66/100 py for CHA2DS2VA >4p. Cumulative incidences with confidence intervals for IS and ICH are depicted in Figure 1a & 1b. Conclusion Overall, the one-year nationwide incidence rate of IS was 2.5-fold higher than the rate of ICH in non-anticoagulated new-onset patients with AF. The cumulative incidences of IS and ICH were highest in groups with high CHA2DS2VA -scores.
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Luojus et al. (2026) conducted a cohort in New-onset atrial fibrillation without oral anticoagulation (n=41,076). Untreated new-onset atrial fibrillation stratified by CHA2DS2-VA score was evaluated on One-year incidence of ischaemic stroke (IS) and intracranial haemorrhage (ICH). Untreated new-onset AF was associated with a 2.5-fold higher 1-year incidence of ischaemic stroke (2.26/100 py) than intracranial haemorrhage (0.88/100 py), peaking in high CHA2DS2-VA groups.
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