Cognitive impairments in chronic heart failure: a case controlled study

There are limited data describing the prevalence, type, and severity of cognitive impairments (CIs) in the general population with chronic heart failure (HF). The primary purpose of this study was to fill this gap in the literature by comparing the cognitive function of patients with chronic HF and community-dwelling control subjects.

A case controlled design was used. Fifty patients with HF were recruited and matched to 50 healthy control subjects on age (+/- 3 years), gender, and estimated intelligence (intelligence quotient +/- 1 standard deviation). In the patient sample, mean left ventricular ejection fraction was 27% +/- 14%, 22 patients had New York Heart Association (NYHA) class II, 23 patients had NYHA class III, and 5 patients had NYHA class IV heart disease. Neuropsychologic tests assessed cognitive outcomes in orientation, attention, memory, executive function, motor speed, and reaction times. Patients had significantly poorer scores than controls on 14 of 19 variables assessed. After standardization of the neuropsychologic test scores to T-scores (mean 50 +/- 10 SD), 23 patients (46%) had mild to severe CI and 8 of the control subjects had mild CI. Both patients and controls were impaired in 1 or more of the 4 memory outcomes assessed. Logistic regression analysis indicated CI was independently associated with HF (odds ratio = 4.47, confidence interval = 1.75-11.43, P < .002). Severity of CI was associated with depressed learning (P < .0001), previous myocardial infarction (MI) (P < .02), and the number of MIs (P < .01). CI severity was not associated with LVEF, HF duration, NYHA class, anxiety, depression, positive affect, social support, or physical functioning. Severity of MI (>or=2 MIs) was associated with deficits in early recall (P < .01), delayed recall (P < .03), and learning (P < .03). In contrast, patients with idiopathic or hypertensive cardiomyopathies without coronary artery disease when compared with patients with greater MI severity were not cognitively impaired on these outcome variables.

The prevalence, type, and severity of CI in the community-dwelling patients with HF are consistent with the results found in patients with end-stage HF awaiting heart transplantation. Patients with heart failure incur a more than 4-fold risk for CI compared with matched community controls. The relationship of MI severity to deficits in memory outcomes and learning suggests that ischemic cardiomyopathy may be a significant factor in the development of CI in heart failure.