Background

Chronic heart failure (CHF) is associated with reduced quality of life (QoL), but underlying mechanisms are incompletely understood. In this study we aimed to assess determinants of both physical and mental functioning in patients with and without chronic heart failure and investigated the impact of physical capacity.

Methods

This is a cross-sectional analysis conducted in two cohort studies using a case-control design. Both, the case cohort (RoC-HF, n=205) and the control cohort (BioPersMed, n=1022) were prospective, single center studies. The case cohort included patients with a previous diagnosis of CHF with reduced ejection fraction and a current left ventricular ejection fraction (LVEF) <50%, while the control cohort included apparently healthy individuals with at least one cardiovascular risk factor. Laboratory parameters, transthoracic echocardiography, physical capacity (Biopersmed: 6-minute walking distance [6MWD]; RoC-HF: 4-meter gait speed [4MGS]), and SF-36 health survey parameters as the main read-out of this study, were available in all participants.

Results

Cases and controls were matched by age and sex yielding a study sample of 188 vs. 188 individuals. Mean age across both cohorts was 64 ± 9 years and 23% were women. NT-proBNP and LVEF (both as median with interquartile range) were 985 (325 – 2183) pg/dl and 37 (30 – 44) % in cases, and 72 (33 - 118) pg/dl and 64 (60 – 68) % in controls.

As expected, cases had lower levels than controls regarding all eight QoL aspects of the SF-36 health survey (Figure 1). Both within the case and the control cohort, measures of heart failure severity (LVEF, NT-proBNP, TAPSE) were not or only marginally associated with SF-36 health survey scales.

In bivariate correlations analyses, physical capacity parameters correlated significantly with physical component summary score (PCS) both within cases and controls, and with mental component summary score (MCS) only in cases (Figure 2). Multivariate linear regression analyses with adjustment for age, sex, eGFR, LVEF, NT-proBNP and TAPSE were conducted in each cohort, respectively. Within cases, 4MGS, but not LVEF, NT-proBNP and TAPSE, was significantly associated with MCS (adjusted beta 0.228, P=0.011) and PCS (beta = 0.318, P<0.001). Within controls, 6MWD was significantly associated with PCS (beta = 0.332, P<0.001), but not with MCS (beta = -0.62, P=0.472).

Conclusion

In patients with CHF, impairment of both physical and mental functioning is determined by physical capacity, but not by measures of cardiac function and congestion. By contrast, only physical functioning, but not mental functioning, can be explained by physical capacity in healthy controls. Given the increasing relevance of QoL as a patient-oriented outcome in CHF, assessment and improvement of physical capacity should be considered essential aspects in CHF care, besides biomarker-guided improvements in cardiac function and congestion. Whether targeting physical capacity, for instance by medical and device therapies, translates into better physical and mental well-being in CHF should be specifically adressed in randomized controlled trials.