Main findings
Although the negative impact of depressive symptomatology on the clinical outcomes of HF has been well documented, there is a gap in understanding the relationship between depressive symptoms and NT-proBNP, a pivotal HF marker. This study addresses this gap by revealing a significant correlation among depressive symptoms, NT-proBNP levels and overall health status.
Nevertheless, our findings diverge from some prior studies, such as those conducted by Van den Broek et al and Lossnitzer et al, where no substantial association between NT-proBNP and depressive symptoms was identified.10 11 Despite this, these studies confirmed the negative influence of these symptoms on clinical outcomes in patients with HF, aligning with the observations in the present study. These discrepancies may be attributed to the use of different assessment instruments. For instance, Broek et al employed the 10-item Center for Epidemiologic Studies Depression Scale, while Lossnitzer et al used the 9-item depression module of the Patient Health Questionnaire, covering depressive symptoms over only 2 weeks.
Given the acknowledged influence of depressive symptoms on HF outcomes, it is reasonable to hypothesise a potential relationship between these symptoms and the HF marker NT-proBNP. This would explain why some patients with HF continue to have high levels of NT-proBNP despite optimal HF management, suggesting that they may be suffering from worsening or unrecognised underlying depression. This aligns with previous studies showing that patients with persistently high levels of NT-proBNP often suffer from unrecognised depressive disorders.17 18 A drawback of these studies, however, is their limited power, as they examined only a single time point. This work is unique as it documents the relationship between both depression scores and NT-proBNP levels over 1 year. These findings could improve the detection and follow-up of depressive symptoms in this group of patients using a biological marker and may help tailor treatment for both HF and depression.
It is crucial to note that correlation does not necessarily imply causation; rather, it suggests a relationship between two variables, indicating they may mutually influence each other. HF leads to chronic cerebral hypoperfusion, systemic inflammation and endothelial dysfunction, all contributing to cognitive impairment and mental illness.19 Moreover, HF symptoms restrict physical abilities and impact health status, triggering feelings of hopelessness and sadness that may culminate in depressive symptomatology.2 Depressive symptoms, in turn, can elevate levels of catecholamine and stress hormones, promoting inflammatory pathways that negatively impact HF progression.20 21 Additionally, patients with depression and HF who receive treatment with antidepressants face a higher risk of medication non-adherence and are less likely to receive guideline-based drug therapy.9 This sets up a vicious circle in which both conditions feed into each other. Recognising a significant correlation between these variables is pivotal for breaking this detrimental cycle. This implies that improvements in either cardiac or mental health have the potential to exert positive influences on the other. This dynamic interplay likely accounts for the observed reduction in depression scores in this study, attributed in part to the optimised HF treatment and the reassurance provided to patients through regular follow-ups.
However, the presence of associations between HF and depressive symptoms, in contrast to the lack of a similar relationship with anxiety in this cohort, remains unclear. The literature on the association between anxiety and clinical outcomes in patients with HF is also debated. In a comprehensive meta-analysis investigating the association between anxiety and HF, nearly half of the included studies failed to establish any significant relationship between anxiety and either HF hospitalisation or mortality in patients with HF.22 23 These findings underscore the critical need for additional research to understand the relationship between mental disorders and HF.
In summary, our study highlights a significant association between depressive symptomatology and NT-proBNP. It emphasises the profound impact of depressive symptoms on clinical outcomes in HF. The valuable insights gained from this research hold the potential to significantly shape a more precisely targeted therapeutic approach for addressing both disorders.