Cross-lagged analyses of the bidirectional relationship between depression and markers of chronic heart failure

Background Depression is common in patients with chronic heart failure (CHF) and is a predictor of rehospitalization and mortality. However, the complex bidirectional relationships between these two conditions are barely understood. We investigated the course of depression and markers of CHF (New York Heart Association [NYHA] functional class, N-terminal-prohormone B-type natriuretic peptide [NT-proBNP], and left ventricular ejection fraction [LVEF]) in a longitudinal study over a period of 2 years, using three assessment points. Methods Data ofn = 446 patients with documented CHF were analyzed using structural equation modeling. Specifically, a Bayesian cross-lagged structural equation model was applied. Results Our study revealed that an aggravation of depression predicted an increase in NYHA functional class (significant cross-lagged effect gamma(h) = 0.103, 95% confidence interval [CI] [0.017; 0.194]), whereas an increase in NYHA functional class did not predict an aggravation of depression (gamma(d) = 0.002 95% CI [-0.057; 0.194]). This association was found only for NYHA functional class and depression-not for NT-proBNP and LVEF. Conclusions Experiencing depression and associated symptoms, such as lack of energy and fatigue, may lead to a further decrease of functional capacity, and consequently to a higher NYHA functional class in CHF patients. As NYHA functional class is associated with higher mortality, this may be a critical development for affected patients. Further studies are required to investigate whether or not this association could be an essential key that explains the pathway from depression to increased mortality in heart failure patients.