Risk of Arterial Ischemic Events After Intracerebral Hemorrhage

Abstract

Background and Purpose- The risk of arterial ischemic events after intracerebral hemorrhage (ICH) is poorly understood given the lack of a control group in prior studies. This study aimed to evaluate the risk of acute ischemic stroke and myocardial infarction (MI) among patients with and without ICH. Methods- We performed a retrospective cohort study using claims data from Medicare beneficiaries from 2008 to 2014. Our exposure was acute ICH, identified using validated <i>International Classification of Diseases, Ninth Revision, Clinical Modification</i> diagnosis codes. Our primary outcome was a composite of acute ischemic stroke and MI, whereas secondary outcomes were ischemic stroke alone and MI alone. We used Cox regression analysis to compute hazard ratios during 1-month intervals after ICH. Sensitivity analyses entailed exclusion of patients with atrial fibrillation and valvular heart disease. Results- Among 1 760 439 Medicare beneficiaries, 5924 had ICH. The 1-year cumulative incidence of an arterial ischemic event was 5.7% (95% CI, 4.8-6.8) in patients with ICH and 1.8% (95% CI, 1.7-1.9) in patients without ICH. After adjusting for potential confounders, the risk of an arterial ischemic event remained significantly increased for the first 6 months after ICH and was especially high in the first month (hazard ratio, 6.7 [95% CI, 5.0-8.6]). In secondary analysis, the risk of ischemic stroke was increased in the first 6 months after ICH (hazard ratio, 6.1 [95% CI, 3.5-9.3]) but the risk of MI was not (hazard ratio, 1.6 [95% CI, 0.3-2.9]). In sensitivity analyses excluding patients with atrial fibrillation and valvular heart disease, the association between ICH and arterial ischemic events was similar to that of the primary analysis. Conclusions- In a large population-based cohort, we found that elderly patients with ICH had a substantially increased risk of ischemic stroke in the first 6 months after diagnosis. Further exploration of this risk is needed to determine optimal secondary prevention strategies for these patients.