Aspirin responsiveness in acute brain ischaemia: Association with stroke severity and clinical outcome

Purpose: Platelets play a critical role in the pathogenesis of acute brain ischaemia. We studied the association between the degree of inhibition of platelet function by aspirin (ASA) and the severity and outcome of acute brain ischaemia. Methods: Platelet responsiveness to ASA was assessed in patients with acute brain ischaemia, treated with ASA since hospital admission. The degree of ASA responsiveness was assessed by optical aggregometry and categorized into patients with good response, partial response and complete unresponsiveness to ASA (good responders, partial responders and non-responders, respectively). An additional evaluation of responsiveness to ASA was performed by Impact-R (cone and platelet analyzer). Patients underwent serial clinical assessment during hospitalization, at discharge and during follow-up. Results: Among 105 patients (mean age 63 ± 12 years; 66% men), impaired ASA responsiveness at baseline as assessed by aggregometry was associated with increased stroke severity at baseline, unfavourable clinical course, and poor functional outcome during follow-up (p < 0.05 for all). Age-adjusted odds ratios in non-responders compared to good responders were 9.8 for severe stroke on admission (95% CI 2.8-34.9), 3.1 for lack of early clinical improvement (95% CI 1.1-8.8) and 8.6 for poor functional outcome during follow-up (95% CI 2.4-30.4). Less robust trends were observed with the Impact-R. Conclusions: Impaired responsiveness to ASA in acute brain ischaemia is common and is associated with worse neurological deficits at stroke onset, early clinical deterioration and poorer functional outcome. The clinical significance of these findings requires further evaluation in larger longitudinal studies.