Verbal learning in cardiac transplant candidates: A preliminary report

Memory dysfunction, psychomotor slowing, and decreased executive function predict mortality in patients with heart failure and low ejection fraction

BACKGROUND

The purpose of this study was to evaluate whether dysfunction of specific cognitive abilities is a predictor of impending mortality in adults with systolic heart failure (HF).

METHODS

A total of 166 stable outpatients with HF completed cognitive function evaluation in language, working memory, memory, visuospatial ability, psychomotor speed, and executive function using a neuropsychological test battery. Demographic and clinical variables, comorbidity, depressive symptoms, and health-related quality of life were also measured. Patients were followed for 12 months to determine all-cause mortality.

RESULTS

There were 145 survivors and 21 deaths. In logistic regression analyses, significant predictors of mortality were lower left ventricular ejection fraction (LVEF) and poorer scores on measures of global congnitive function Mini-Mental State Examination [MMSE], working memory, memory, psychomotor speed, and executive function. Memory loss was the most predictive cognitive function variable (overall chi(2) = 17.97, df = 2, P < .001; Nagelkerke R(2) = 0.20). Gender was a significant covariate in 2 models, with men more likely to die. Age, comorbidity, depressive symptoms, and health-related quality of life were not significant predictors. In further analyses, significant predictors of mortality were lower systolic blood pressure and poorer global cognitive function, working memory, memory, psychomotor speed, and executive function, with memory being the most predictive.

CONCLUSIONS

As hypothesized, lower LVEF and memory dysfunction predicted mortality. Poorer global cognitive score as determined by the MMSE, working memory, psychomotor speed, and executive function were also significant predictors. LVEF or systolic blood pressure had similar predictive values. Interventions are urgently needed to prevent and manage memory loss in HF.

Cognitive impairment in heart failure: a systematic review of the literature

BACKGROUND

Heart failure (HF) and cognitive impairment are common medical conditions that are becoming increasingly prevalent in the aging Western population. They are associated with frequent hospitalisation and increased mortality, particularly when they occur simultaneously. Evidence from a number of studies suggests that HF is independently associated with impairment in various cognitive domains.

AIMS

This systematic literature review evaluates the relation between cognitive deterioration and heart failure.

METHODS

We searched electronic databases from 1966 to May 2006 for studies that investigated cognitive function in HF patients. Twenty-two controlled studies that met the inclusion criteria were selected for analysis. Study characteristics and data on global cognitive performance, memory scores, psychomotor speed and depression scores were extracted and analysed using the Cochrane Review Manager software.

RESULTS

Pooled analysis shows diminished neuropsychological performance in HF patients, as compared to control subjects. In a pooled sample of 2937 heart-failure patients and 14,848 control subjects, the odds ratio for cognitive impairment was 1.62 (95% confidence interval:1.48-1.79, p<0.0001) among subjects with HF.

CONCLUSION

This review confirms the relationship between HF and cognitive impairment, but it also stresses the need for additional systematic neuropsychological data and adequate neuro-imaging from representative populations of HF patients.

Cognitive Dysfunction in Advanced Heart Failure and Prospective Cardiac Assist Device Patients

BACKGROUND

Extended periods of hypoperfusion in an advanced heart failure (HF) places patients at high risk for neurobehavioral compromise, which has not been studied systematically. It is also not clear how intravenous inotropic therapy and mechanical cardiac assist devices (MCAD) affect cognitive function.

METHODS

This prospective cross-sectional cognitive preliminary study evaluated 252 potential heart transplant candidates assessing functions in memory, motor, and processing speed. Patients were divided into three HF groups based on severity of disease: group 1 outpatients (n = 113), group 2 in-patients requiring inotropic infusion (n = 83), and group 3 inpatients likely requiring MCAD support (n = 56). Aggregate z-scores for memory, motor, and processing speed and independent samples t tests assessed intergroup differences on 13 cognitive measures.

RESULTS

A broad pattern of cognitive impairment was observed within the advanced HF group; fewer deficits were found in group 1 outpatients and more severe deficits in group 3 MCAD subjects. A difference in motor functions was observed as the earliest abnormality, with group 3 showing significant changes compared with group 1. The most dramatic changes were seen in domain mental processing speed along with specific verbal and visual memory functions, which were slower in group 3 compared with groups 1 and 2.

CONCLUSIONS

Cognitive deficits are common in advanced HF and worsen with increasing severity of HF. Appropriately designed and randomized studies will be needed to demonstrate if earlier MCAD implantation is warranted to arrest cognitive dysfunction and better postimplantation adaptation.

Systemic hypoperfusion is associated with executive dysfunction in geriatric cardiac patients

The present study examines the relationship between systemic hypoperfusion via cardiac output (CO) and neuropsychological performances emphasizing executive function in an aging cohort. Geriatric outpatients with treated, stable cardiovascular disease (CVD) and no history of neurological illness (n=72, ages 56-85) were administered cognitive measures with an emphasis on executive functioning. Echocardiogram findings were used to stratify participants into two groups: low CO (<4.0 L/min) and normal CO (> o r=4.0 L/min). Between-group comparisons were made using ANCOVAs adjusting for systolic blood pressure. The low CO group performed significantly worse than the normal CO group on DKEFS Tower Test and DKEFS Trail Making Test. No significant between-group differences were noted for any of the other cognitive indices. Findings suggest that reduced CO is associated with poorer executive functioning among geriatric outpatients with stable CVD, as the cognitive profile emphasizes a relationship between systemic hypoperfusion and problems with sequencing and planning. The executive dysfunction profile may be secondary to reduced blood flow to vulnerable subcortical structures implicated in frontal-subcortical circuitry.

Cognitive function in adult cardiothoracic transplant candidates and recipients

Innovative surgical and medical techniques have prolonged the life span of cardiothoracic (CT) transplant recipients and made transplantation an option for many older patients. Cognitive function is a key determinant of the CT transplant recipient's ability to manage the complex treatment regimen and experience optimum benefit of the procedure. As the CT population ages, risk of cognitive dysfunction due to normal aging is compounded by the physical and mental changes associated with end-stage organ disease, comorbid conditions, and transplant-related complications. Cognitive abilities consist of (a) receptive functions (ability to select, acquire, classify, and integrate information); (b) memory and learning (ability to store and retrieve information); (c) thinking (ability to mentally organize and reorganize information; and (d) expressive functions (ability to communicate or act upon information). Although each of these functions represents a distinct type of behavior, they are interdependent. The purpose of this article is to (a) discuss the literature regarding cognitive function before and after adult heart, lung, and heart-lung transplantation; (b) identify methodological problems associated with the studies done to date; and (c) make recommendations for future research in this area.

Cognitive deficits in patients with heart failure: a review of the literature

PURPOSE

Chronic heart failure (HF) and cognitive impairments (CI) are common problems in the elderly. Both are associated with increased mortality and disability, decreased quality of life, and increased health care costs. While these conditions may occur by chance in the same individual, there is increasing evidence that HF is independently associated with CI. The purpose of this article is to review and critique the literature addressing the prevalence, type, and severity of CI in HF patients, the clinical factors associated with CI, and the potential pathophysiology underlying the development of CI, and to recommend priority areas for future research.

RESULTS

Memory and attention deficits are the most frequently occurring CI in this patient population, followed by slowed motor response times and difficulties in problem solving. Prevalence rates range from 30% to 80% depending upon the age of the patients and the characteristics of the sample being studied. Most patients have mild impairments, although as many as one fourth may have moderate to severe CI. The relationship between left ventricular ejection fraction and cognition is inconsistent and may be nonlinear. The pathophysiology underlying the development of CI in HF patients may be related to both cerebral infarction and cerebral hypoperfusion either alone or in combination.

CONCLUSIONS

The current literature is limited by studies with sometimes small or nonrepresentative samples, few matched control studies, and lack of longitudinal data that could indicate the conditions that favor the development of CI over time. Future research needs to focus on (1) determining the types, frequency, and severity of impairments in cognitive functioning among a representative sample of HF patients, (2) explicating the pathological mechanisms and the clinical factors that underlie the development of cognitive deficits, and (3) identifying the ways CI influences quality of life. Interventions can then be developed to prevent or delay the occurrence of CI or to minimize their effect on patient self-management and quality of life.

Activities of daily living among heart transplant candidates: neuropsychological and cardiac function predictors

BACKGROUND

The ability of patients to perform day-to-day tasks (e.g., medication management, dietary regulation) is an important concern of transplant teams.

METHODS

We studied a clinical series of 75 heart transplant candidates and 38 controls to examine the predictive validity of demographic, neuropsychologic, and cardiac function variables to a performance-based measure of instrumental activities of daily living (IADL) capacity (i.e., Everyday Problems Test, EPT).

RESULTS

Multiple regression analyses, controlling for education and race, indicated that neuropsychologic tests accounted for between 34% and 67% of the variance across IADL domains (e.g., cooking, household chores, medication management). The IADL capacity was most consistently predicted by long-standing verbal ability (Shipley Institute of Living Scale-Vocabulary, SILS-VOC) and psychomotor speed and mental flexibility (Trail Making Test-Part B, TMT-B). Similarly, SILS-VOC and TMT-B also tended to show the best operating characteristics (i.e., sensitivity, specificity, positive predictive power, negative predictive power) for detection of dependence across IADL domains. In contrast, cardiac function measures (e.g., cardiac output, mean atrial pressure) were largely unrelated to the patient's performance on the paper-and-pencil EPT task.

CONCLUSIONS

Long-standing intellectual ability, and a measure of speeded information processing and mental flexibility are the best predictors of IADL capacity.

The relationship between cardiac function and neuropsychological status among heart transplant candidates

BACKGROUND

Cognitive deficits among heart transplant candidates have been well documented. This study was designed to examine the hypothesis that impaired cognitive test performance among heart transplant candidates may be attributed, in part, to decreased cerebral perfusion secondary to poor cardiac function.

METHODS AND RESULTS

Sixty-two patients participated in the study who underwent heart catheterization within 1 day of completing a battery of cognitive tests. Multiple demographic and patient characteristics were examined for their potential moderating role in the relationship between measures of cardiac function and cognitive performance including age, education, race, gender, psychiatric history, medication usage, cardiac surgical history, and self-reported symptoms of depression and anxiety. Only age and education were significantly related to cognitive performance (P < .01). Thus, partial correlation analyses controlling for age and education were used to examine the relationship between cardiac function and cognitive performance. In general, increasing hemodynamic pressure variables (ie, pulmonary artery pressure and right atrial pressure), and to a lesser extent cardiac output and cardiac index, were related (r = - .32 to - .43; P < .01) to decreased performance on cognitive tasks that assessed simple attention, speed of mental processing, and mental flexibility (Digit Span-Forward, Trail Making Test-Part B, Symbol Digits Modalities Test, and Stroop Neuropsychological Screening Test). Left ventricular ejection fraction, systemic and pulmonary vascular resistance, and mean arterial pressure were largely unrelated to cognitive performance in this sample of patients with end stage cardiac disease.

CONCLUSIONS

Hemodynamic pressure variables seem to be most consistently related (ie, inversely) to cognitive functioning among heart transplant candidates.

Memory improvement following cardiac transplantation

Seventeen patients with severe cardiomyopathy underwent neuropsychological evaluation prior to and at least 1 year after successful heart transplantation. Study candidates were screened, and individuals with a history of stroke, cardiac arrest, or medical and neurological conditions which might affect brain function were excluded. Pre-transplant testing revealed normal intelligence and normal attentional, language, and executive abilities but impaired recent memory. Following heart transplant, memory functioning improved significantly, reaching normal levels. Other cognitive abilities remained unchanged. Results suggest that cardiomyopathy is associated with mesial temporal dysfunction, possibly attributable to inadequate or reduced cerebral blood flow and related hypometabolism. This cerebral dysfunction is potentially reversible following successful transplantation, which restores cardiac output and cerebrovascular perfusion.