Anticoagulants as more effective secondary prevention for embolic stroke of undetermined source: retrospective cohort study

Abstract Background: Whether anticoagulants or antiplatelets are more effective for secondary stroke prevention for embolic stroke of undetermined source (ESUS) remains unknown. These two treatments were compared retrospectively. Methods: Of 779 acute ischemic stroke inpatients between January 2012 and December 2014 in our stroke center, 110 patients met our ESUS criteria were compared. Antiplatelets were used in 81 patients, and anticoagulants were used in 29. ESUS criteria by Hart et al., except for extracranial atherosclerosis, were used. In all patients, intracranial magnetic resonance angiograms were obtained, and the infarct was diagnosed with positive diffusion studies. The primary outcome was recurrence-free survival. Score-tests for the hazard ratio assumption and for covariate effects in the Cox proportional hazard model were performed. To estimate hazard ratios, a likelihood ratio test and the Kaplan-Meier method and log-rank test were used. This study protocol was approved by the Institutional Review Board of the hospital. Results: The mean follow-up period was 84.0±65.5 weeks, and 14 patients treated with antiplatelets and one treated with anticoagulants developed recurrent ischemic stroke. The antiplatelet group had a significantly higher risk of recurrence than the anticoagulant group (p=0.0293, likelihood ratio 0.144, 95% confidence interval [CI]: 0.019-1.096). Multivariate analysis also showed a similar result (p=0.013, likelihood ratio -1.94, 95% CI: 0.01-0.72, respectively). Conclusions: These findings suggest that anticoagulants are more effective than antiplatelets for secondary stroke prevention for ESUS patients, although this was a non-randomized, single-center, retrospective analysis with a small sample size. Further studies are needed to accumulate enough evidence.