C-Reactive Protein and Long-Term Risk of Stroke in Patients with Myocardial Infarction

Background: Patients with myocardial infarction (MI) are at increased risk of ischemic stroke (IS). We previously showed that the biomarker C-reactive protein (CRP) is associated with an increased long-term risk of both death and heart failure in patients with MI. The long-term prognostic value of CRP to determine the risk of IS in such individuals is unknown. Aim: To assess the association between CRP and long-term risk of IS in patients with MI and no previous history of IS or transient ischemic attack (TIA). Methods: We used Danish nationwide registries to identify patients without prior IS or TIA who presented with a diagnosis of MI from 2013 through 2020 and who had a CRP measurement ≦24 hours of index hospitalization. The primary endpoint was IS. Cumulative incidence curves were constructed for the outcome at 0-30 and 31-365 days. We used multivariable Cox regression with average treatment effect modeling to render standardized absolute and relative risks of IS at 0-30 and 31-365 days according to CRP quartiles. Models were adjusted for demographics and clinical features, including high-sensitivity troponin concentrations. Results: After exclusion of 2,313 patients with a history of IS or TIA, the final cohort comprised 26,722 individuals. Median CRP was 4 mg/l, and quartile intervals were: quartile 1: <2.9 mg/l, quartile 2: 2.9 to <4 mg/l, quartile 3: 4 to <12 mg/l, and quartile 4: ≥12 mg/l. Patients in quartile 4 were older and had a higher prevalence of comorbidities, including hypertension, diabetes, and atrial fibrillation. At 0-30 days, 109 patients were diagnosed with IS and an additional 182 were diagnosed with IS at 31-365 days. The standardized absolute risk of IS was lowest in CRP quartile 1 at both 0-30 days (4.0 % (Figure 1) and 31-365 days (5.6 %) (Figure 2). For example, the relative risks of IS for quartile 4 vs. quartile 1 were 1.89 (95 % CI 0.94-2.84) at 0-30 days and 1.46 (95 % CI 0.80-2.11) at 31-365 days. Conclusion: In patients with MI and without prior IS or TIA, higher CRP concentrations appeared to be associated with a higher risk of IS at both one month and one year.