Blood Biomarkers for the Differentiation of Cardiac Ischemic Stroke Subtypes: A Systematic Review

Background: Blood biomarkers are a cost-effective and valid method to diagnose ischemic stroke and differentiate its subtypes in countries with poor resources. Objective: To perform a systematic review of published literature evaluating the diagnostic utility of blood-based biomarkers to diagnose and differentiate the etiology of ischemic stroke. Methods: A comprehensive literature search was carried out till December 2017 in major scientific and medical databases including PubMed, Cochrane, OVID and Google Scholar. Modified Quality Assessment of Diagnostic Accuracy Studies questionnaire was used to assess the methodological quality of each study. Results: Twenty-six studies were identified relevant to our systematic review. Various biomarkers have been studied, though only a few biomarkers such as a B-type natriuretic peptide (BNP) and Ddimer have proved their clinical utility. None of the other tested biomarkers appeared to have consistent results to diagnose ischemic stroke subtypes. Most of the studies had limitations in the classification of ischemic stroke, sample size, sample collection time, methods, biomarker selection and data analysis. Conclusion: Our systematic review does not recommend the use of any blood biomarker for clinical purposes based on the studies conducted to date. BNP and D-dimer may present optimal biomarker for diagnosis and differentiation of ischemic stroke. However, large well-designed clinical studies are required to validate utility of these biomarkers to differentiate subtypes of ischemic stroke.