Introduction: Preconditioning improves acute ischemic stroke (AIS) outcomes in animals and possibly in humans. The influence of a preceding ischemic event (PIE), such as a TIA or AIS occurring at different intervals, sites and for different durations, needs to be studied in humans.
Hypothesis: We aimed to identify whether a PIE can have a preconditioning effect on a subsequent AIS.
Methods: Using consecutive AIS from the ASTRAL registry we determined demographics, risk factors, past medical history,stroke mechanism,PIE and other features that were associated with initial stroke severity measured by NIHSS. We used a multivariate linear regression model with NIHSS as the dependent variable to compare groups with and without PIE.
Results: Of 3501 consecutive AIS patients (43% females, median age 73 y), 996 (28.4%) had preceding PIEs (15.7% TIA, 12.9% ischemic stroke, 2.4% retinal ischemia, 8.8% multiple events). There were 162 acute PIE in the preceding 24 h, and 94 subacute PIE up to 7 d before the stroke, respectively with a median delay between the PIE and the subsequent stroke of 180 days.Results of the adjusted multivariate regression analysis are shown as forest plots below.
Conclusions: In patients with AIS, we found an independent association between lesser stroke severity and PIE, suggesting a possible beneficial role of ischemic preconditioning in stroke in humans. The effect of timing, severity,location of PIE and long-term outcome of such patients needs to be analyzed in further studies.