There is increasing evidence of an association between chronic heart failure (CHF) and cognitive impairment, resulting in worse health outcomes. Various medical screening tests have been identified as essential in the diagnosis and long-term management of CHF. Regardless, recommendations and consensus in screening for cognitive impairment have been overlooked. Increased recognition of this significant comorbidity is required to develop strategies to ensure improved patient health outcomes.

We read with interest the study conducted by Harkness et al, who investigated screening for cognitive deficits in a cohort of elderly patients with CHF. This study highlights the hidden nature of cognitive impairments that although mild in nature may have significant implications for health outcomes in this vulnerable group of patients.

Other studies have demonstrated that cognitive impairment occurs in as many as 3 out of 4 patients with CHF, and there is escalating evidence that this co-morbidity is associated with worse health outcomes. Unless purposefully screened for, cognitive impairment is largely hidden, making it difficult for many patients to independently recognize symptom changes and make appropriate self-care decisions. Thus, cognitive impairment is an important but underrecognized complication of CHF.

Most recently, cognitive impairment affecting memory, psychomotor speed, and executive functions was identified as a significant predictor of mortality in 166 patients with stable CHF. In this study, although most patients were judged as not cognitively impaired using the Mini-Mental State Examination (MMSE), the 21 patients who subsequently died were judged as cognitively impaired. Because of mounting evidence that cognitive impairment is a significant health problem in patients with CHF, screening for this co-morbidity has been advocated as part of routine clinical assessment in patients with CHF.

Weighing the benefits and harms of screening is essential when determining the value of patient screening. Harms from screening include medical complications (i.e., false-negatives findings delaying treatment), psychological consequences (i.e., unnecessary labeling), and adverse legal and economic outcomes. The value of screening is ultimately determined by its effect on morbidity, mortality, and disability. Restricting screening to individuals who are at high risk for disease significantly increases the benefits through defining health policy. Cognitive impairment occurs in as many as 75% of patients with CHF. Various medical screening tests are considered essential in the diagnosis and long-term management of CHF. However, scant attention has been given to screening for cognitive aspects. Subsequently, the question remains as to how and when screening should be undertaken.

To date, no consensus has been achieved on screening for cognitive impairment in patients with CHF. Most studies include one of a variety of global screening measures and/or any number of tasks from comprehensive neuropsychological tests. Although neurocognitive testing performed by a mental health clinician is considered the gold standard for the evaluation and diagnosis of brain pathologies, it is not feasible for every patient with CHF to undergo such comprehensive assessment. The purchase, administration, and interpretation of neurocognitive tests require specialized licensing and training, preferably by a neuropsychologist. Most CHF management programs do not have access to a neuropsychologist unless conducting research studies specifically investigating this co-morbidity. Neurocognitive testing needs to be conducted in quiet clinical settings with minimal distraction, a scenario atypical in hospital wards. These tests are also time-consuming to administer, taking 1 to 2 hours. This in itself can impose an extra burden on patients who are already fatigued and sleep deprived. Screening using global cognitive function measures is the most practical method to identify vulnerable patients with CHF who require management aimed at minimizing the impact of this co-morbidity. In the event that cognitive impairments persist, a more comprehensive and in-depth assessment of cognitive function to diagnose brain pathology would be warranted.

Global screening measures such as the MMSE and the Montreal Cognitive Assessment assess a variety of cognitive domains, including working memory, visual construction, expressive language, verbal memory, and recall. The MMSE, originally developed for dementia screening yet used widely in studies investigating cognitive impairment in patients with CHF, is also known to have limited sensitivity in detecting mild forms of cognitive impairment. Mild cognitive impairment (MCI) is more dominant than dementia in patients with CHF, so screening methods need to be sensitive and specific to detecting MCI. The Montreal Cognitive Assessment, which was specifically developed to identify MCI in patients who would otherwise have scored within the normal range on the MMSE, offers hope. However, it should be noted that several recent studies have suggested that the recommended cut-off score has low specificity at ruling out amnesic or multidomain MCI, indicating that more research is required on determining the most appropriate cut-off threshold.

The importance of identifying MCI in patients with CHF cannot be underestimated, as this co-morbidity is a predictor of poor health outcomes, including an increased risk for progression to dementia. By identifying impairments in specific cognitive domains, patient management plans can be tailored to individual patients to minimize the debilitating effects and individualize educational and monitoring strategies. It is now time for consensus and recommendations guiding the screening for cognitive impairment in patients with CHF, including the tools to use, their cut-off thresholds, and when and how often assessments should be conducted. By doing so, this will validate the significance of this co-morbidity and its relation with health outcomes.