S100B Serum Levels in Chronic Heart Failure Patients: A Multifaceted Biomarker Linking Cardiac and Cognitive Dysfunction.

S100 calcium-binding protein B (S100B) is a protein primarily known as a biomarker for central nervous system (CNS) injuries, reflecting blood-brain barrier (BBB) permeability and dysfunction. Recently, S100B has also been implicated in cardiovascular diseases, including heart failure (HF). Thus, we investigated serum levels of S100B in 146 chronic HF patients from the Cognition.Matters-HF study and their association with cardiac and cognitive dysfunction. The median S100B level was 33 pg/mL (IQR: 22-47 pg/mL). Higher S100B levels were linked to longer HF duration ( = 0.014) and increased left atrial volume index ( = 0.041), but also with a higher prevalence of mild cognitive impairment ( = 0.023) and lower visual/verbal memory scores ( = 0.006). In a multivariable model, NT-proBNP levels independently predicted S100B (T-value = 2.27, = 0.026). S100B did not impact mortality (univariable HR (95% CI) 1.00 (0.99-1.01); = 0.517; multivariable HR (95% CI) 1.01 (1.00-1.03); = 0.142), likely due to its reflection of acute injury rather than long-term outcomes and the mild HF phenotype in our cohort. These findings underscore S100B's value in comprehensive disease assessment, reflecting both cardiac dysfunction and potentially related BBB disruption.