Background and purpose A subset of ischaemic stroke patients with atrial fibrillation (AF) have ischaemic stroke despite anticoagulation. We sought to determine the association between prestroke anticoagulant therapy and recurrent ischaemic events and symptomatic intracranial haemorrhage (sICH).
Methods We included consecutive patients with acute ischaemic stroke and AF from the Initiation of Anticoagulation after Cardioembolic stroke (IAC) study from eight comprehensive stroke centres in the USA. We compared recurrent ischaemic events and delayed sICH risk using adjusted Cox regression analyses between patients who were prescribed anticoagulation (ACp) versus patients who were naïve to anticoagulation therapy prior to the ischaemic stroke (anticoagulation naïve).
Results Among 2084 patients in IAC, 1518 had prior anticoagulation status recorded and were followed for 90 days. In adjusted Cox hazard models, ACp was associated with some evidence of a higher risk higher risk of 90-day recurrent ischaemic events only in the fully adjusted model (adjusted HR 1.50, 95% CI 0.99 to 2.28, p=0.058) but not increased risk of 90-day sICH (adjusted HR 1.08, 95% CI 0.46 to 2.51, p=0.862). In addition, switching anticoagulation class was not associated with reduced risk of recurrent ischaemic events (adjusted HR 0.41, 95% CI 0.12 to 1.33, p=0.136) nor sICH (adjusted HR 1.47, 95% CI 0.29 to 7.50, p=0.641).
Conclusion AF patients with ischaemic stroke despite anticoagulation may have higher recurrent ischaemic event risk compared with anticoagulation-naïve patients. This suggests differing underlying pathomechanisms requiring different stroke prevention measures and identifying these mechanisms may improve secondary prevention strategies.
Data availability statement
Data are available on reasonable request.
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Contributors SY, NH, AdH: Study concept design, drafting manuscript, and statistical analysis. JAG, CRLG, EM, ALL, DA, AL, MN, AK, IA, BMG, HF, KBE, HP, HM, JT, MV, CE, NC, KM, IM-N, MS, KLF, SGK, AN and MK: data collection and manuscript revisions. ESc and TT: data management and manuscript revision. ESm and MEG: study concept and design and manuscript revision.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests SY has a non-funded research collaboration with Medtronic. MEG reports grants from AVID (Eli Lilly), grants from Boston Scientific, and grants from Pfizer outside the submitted work. NH reports grants from NINDS during the conduct of the study; grants from NICHD of the NIH, grants from NINDS of the NIH, grants from CDMRP of the DoD, and personal fees from Astrocyte Pharmaceuticals outside the submitted work. EM reports grants from NIH/NINDS outside the submitted work. AdH reports research support from AMAG and Regeneron.
Provenance and peer review Not commissioned; externally peer reviewed.