Variation in blood viscosity based on the potential cause of stroke of undetermined etiology

Abstract

Background: This study investigated potential differences in blood viscosity (BV) among patients with stroke of undetermined etiology, negative evaluation (SUDn), specifically those with potential atherothrombosis (SUDn-AT) and those with possible embolism (SUDn-E).Methods: This single-center study employed a retrospective observational design. The participants were patients over 20 years old with the SUDn stroke subtype who were admitted within 5 days of symptom onset. These patients were categorized as SUDn-AT or SUDn-E. Patients in the SUDn-AT group had nonsignificant stenosis (<50%) of a major brain artery relevant to their symptoms and exhibited one or more signs of systemic atherosclerosis, including atherosclerosis of at least one major brain artery other than those clinically relevant, coronary artery disease, and/or peripheral artery disease. For the SUDn-E group, the SUDn criteria from the TOAST (Trial of Org 10172 in Acute Stroke Treatment) classification system were strictly applied.Results: The final analysis included 153 patients, with 104 (68%) classified as SUDn-E and the remaining 32% as SUDn-AT. Patients in the SUDn-AT group had a higher systolic BV (P=0.012) and diastolic BV (P=0.020) than those in the SUDn-E group. Multivariable logistic regression analysis revealed that age (odds ratio [OR], 1.08; 95% confidence interval [CI], 1.03–1.13; P=0.003), systolic BV (OR, 3.11; 95% CI, 1.41–6.85; P=0.005), and diastolic BV (OR, 1.08; 95% CI, 1.02–1.14; P=0.009) were associated with SUDn-AT.Conclusions: Within the TOAST system, two SUDn entities may be distinguishable, with potentially different underlying etiologies: atherothrombosis and embolic stroke of undetermined source.