Abstract WP237: High Platelet Counts Associate with Ischemic Lesions in Spontaneous Intracerebral Hemorrhage Patients

Background and Purpose: Diffusion weighted imaging (DWI) ischemic lesions identified after intracerebral hemorrhage (ICH) are known to associate with poor outcomes. These lesions may be attributable to microthrombosis, yet it is unclear whether specific thrombotic risk factors for ICH patients contribute to increased DWI lesion risk. We sought to assess whether increased platelet counts associate with DWI lesions after ICH. Methods: Hospitalized acute spontaneous ICH patients with baseline platelet counts and inpatient magnetic resonance imaging (MRI) were assessed from a single-center ICH cohort and a separate external, multi-center validation ICH cohort. Patients with systemic coagulopathy unrelated to platelet counts (PT>20, PTT>50, INR >1.7) were excluded. Baseline platelet count was assessed as a continuous exposure variable. DWI ischemic lesion presence was defined as the primary outcome. The relationship of platelet counts with DWI lesion presence was assessed using multivariable logistic regression models adjusting for baseline characteristics, ICH score, time between admission and MRI, and change in systolic blood pressure within first 24 hours of admission. Secondary analyses were performed stratified by ICH location in the validation cohort. Results: We identified 184 and 874 ICH patients for analyses from the primary and external validation cohorts, respectively. Mean baseline platelet count was 226.2 and 229.7 and DWI lesions were present in 30% and 27% of patients from each cohort, respectively. In our primary single-center cohort, higher platelet counts significantly associated with DWI lesions (adjusted OR per 10,000 platelets/uL 1.063 [95% CI 1.002-1.127]). We identified similar relationships in our multi-center validation cohort (adjusted OR 1.029 [1.006-1.052]). Stratified analyses by ICH location revealed that these relationships were again seen in lobar ICH patients (adjusted OR 1.041 [1.004-1.079]) but not deep ICH (adjusted OR 1.020 [0.991-1.050]). Conclusion: Higher baseline platelet counts are associated with ischemic lesions in spontaneous ICH patients, with lobar ICH patients more vulnerable to this relationship. Given ongoing work to assess DWI lesion prevention with antithrombotic medications, further work is required to clarify whether these findings can help target DWI lesion prevention and treatment strategies.