Background: Cognitive impairment interfering with therapy adherence and outcome is a frequent and serious comorbidity in patients with chronic heart failure (HF). Besides humoral and immunologic factors, reduced cerebral blood flow constitutes a potential connection between cardiac dysfunction and associated cognitive decline beyond aging.

Methods: Using non-invasive extracranial sonography, we quantified internal carotid artery (ICA) blood flow in chronic HF patients participating in the prospective Cognition.Matters-HF study. One hundred forty-six subjects aged 32 to 85 years (15.1% women) were extensively phenotyped, including comprehensive cognitive testing of five separate domains and magnetic resonance imaging (MRI) of the brain.

Results: Left (307±70 ml/min) and right (307±71 ml/min) ICA flow significantly correlated (ρ=0.45) and total ICA flow of both sides ranged from 320 to 1010 ml/min (median 600 ml/min). HF patients with atrial fibrillation (n=34; 539±83 ml/min) displayed reduced ICA flow when compared to patients in sinus rhythm (n=102; 637±124 ml/min; p<0.001). In patients with sinus rhythm, HbA1c levels predicted ICA flow significantly (ρ=-0.26; p=0.007) and related to cerebrovascular resistance index (ρ=0.31; p<0.001). MRI analyses revealed that reduced ICA blood flow associated with hippocampal atrophy, measured by Scheltens score (ρ=-0.33; p<0.001). Of note, ICA flow (T=-2.04) and atrial fibrillation (T=2.66) were independent predictors (R²=0.22) of hippocampal atrophy beyond aging (T=3.59). Cognitive testing, which was normalized for age, gender and education, showed that ICA flow itself strongly correlated to executive function (ρ=0.31; p<0.001), represented by the domains working memory (ρ=0.24; p=0.003) and visual/verbal fluency (ρ=0.29; p<0.001). In line, patients with executive dysfunction (defined as underperformance in at least one of the domains selectivity of attention, working memory and visual/verbal fluency; n=75) had reduced ICA flow (581±100 ml/min) when compared to those without (645±134 ml/min; p=0.001).

Conclusions: Independently of atrial fibrillation, ICA flow predicts hippocampal atrophy and executive dysfunction in chronic HF patients. Thus, this non-invasive and widely available technique might help detecting and stratifying patients at risk for cognitive impairment.