Mechanisms of ischaemic strokes and transient ischaemic attacks despite oral anticoagulation in patients with atrial fibrillation.
KM, M., V, F., R, K., & HD, W. (2026). Mechanisms of ischaemic strokes and transient ischaemic attacks despite oral anticoagulation in patients with atrial fibrillation.. The New Zealand medical journal. https://doi.org/10.26635/6965.7380
KM M, V F, R K, HD W. Mechanisms of ischaemic strokes and transient ischaemic attacks despite oral anticoagulation in patients with atrial fibrillation.. The New Zealand medical journal. 2026; doi: 10.26635/6965.7380
KM M, V F, R K, et al. Mechanisms of ischaemic strokes and transient ischaemic attacks despite oral anticoagulation in patients with atrial fibrillation.[J]. The New Zealand medical journal. 2026. DOI: 10.26635/6965.7380.
@article{km2026,
author = {Mahawish KM and Feigin V and Krishnamurthi R and White HD},
title = {Mechanisms of ischaemic strokes and transient ischaemic attacks despite oral anticoagulation in patients with atrial fibrillation.},
journal = {The New Zealand medical journal},
year = {2026},
doi = {10.26635/6965.7380},
note = {PMID: 42275655},
}
TY - JOUR AU - Mahawish KM AU - Feigin V AU - Krishnamurthi R AU - White HD TI - Mechanisms of ischaemic strokes and transient ischaemic attacks despite oral anticoagulation in patients with atrial fibrillation. T2 - The New Zealand medical journal PY - 2026 DO - 10.26635/6965.7380 AN - PMID:42275655 ER -
AIMS: The aim of this article was to characterise the mechanisms underlying "breakthrough" ischaemic stroke (IS) or transient ischaemic attack (TIA) despite oral anticoagulation in patients with atrial fibrillation (AF). METHODS: We conducted a cross-sectional analysis of adults with non-valvular AF who experienced IS/TIA in the fifth Auckland Regional Community Stroke Study (ARCOS V: September 2020 to August 2021). Using clinical records, we collected data on demographics, comorbidities and peri-event anticoagulant dosing and intake. Anticoagulant adherence in the months preceding IS/TIA was categorised as good control if proportion of days covered (PDC) ≥80% for direct oral anticoagulant users or time in therapeutic range (TTR) ≥70% for warfarin users. IS/TIA mechanism was adjudicated using standardised criteria and classified as cardioembolic or non-cardioembolic, and patient characteristics were compared. RESULTS: Among 179 patients (76/179 [43%] female), 138/179 events (77%) were adjudicated as cardioembolic, while the remainder were attributed to competing mechanisms. Compared with non-cardioembolic events, cardioembolic aetiology was associated with younger median age (72 vs 81 years), lower proportions with good anticoagulant control (87/138 [63%] vs 34/41 [83%], p=0.017) and higher rates of peri-event missed or under-dosing (90/138 [65%] vs 18/41 [44%], p=0.014). In multivariable analysis, good control was independently associated with higher odds of a non-cardioembolic mechanism (adjusted odds ratio 3.67 [95% confidence interval 1.35-9.99], p=0.011). CONCLUSION: Most breakthrough IS/TIA events on oral anticoagulation were either associated with anticoagulant under-exposure (in patients with a cardioembolic aetiology) or a competing mechanism rather than anticoagulant failure. These findings highlight the importance of careful assessment to inform appropriate secondary prevention strategies.