The apparent increase in risk for hemorrhagic stroke among patients with previous infective endocarditis (IE) was explained by the mediating factors of mechanical heart valve insertion, atrial fibrillation, and anticoagulation medication, according to a study published in Clinical Infectious Diseases.

A register-based cohort of 9 million people in Denmark was used to propensity score match patients with left-sided IE from 1977 to mid-2015 with IE-free individuals (1:10). Follow-up of patients began 1 year after diagnosis with IE.

Compared with the matched cohort, patients with IE had a higher long-term risk for hemorrhagic stroke (hazard ratio, 1.47; 95% CI, 1.20-1.80; P =.0002); this was particularly increased in patients in the lowest propensity score quartile (hazard ratio, 2.60; 95% CI, 1.89-3.58; P =.0007). Mediation analysis suggested that the indirect effects of insertion of a mechanical heart valve, atrial fibrillation, or treatment with anticoagulants could explain the increased risk. The cumulative risk for hemorrhagic stroke in patients with IE 30 years from the start of follow up was 3.0%.

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One potential limitation to the results is the fact that most IE diagnosis codes do not include which valve was affected, but the 17% of patients excluded with presumed right-side IE is higher than expected. Further, the exclusion of high-risk patients such as intravenous drug users, who often present with severe staphylococcal infection, may limit the generalized applicability of results, as IE in these patients is not exclusively right-sided.

The results here indicate that it is not IE; specifically, that increases long-term risk for hemorrhagic stroke after the first year, and thus “does not support cerebral imaging as a routine in the long-term follow-up if the patient has no known cerebrovascular abnormalities and is asymptomatic at discharge.” However, the role of cerebral imaging during the acute phase of IE disease was beyond the scope of this work.

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Klein CF, Gørtz S, Wohlfahrt J, et al. Long-term risk of hemorrhagic stroke in patients with infective endocarditis: a Danish nationwide cohort study [published online June 16 2018]. Clin Infect Dis. doi: 10.1093/cid/ciy512