Physical functioning predicts cognition in systolic heart failure

Background Physical and cognitive deficits often coexist as comorbidities in individuals with chronic heart failure (CHF). Commonly used in clinical settings, the 6-minute walking test (6MWT), Timed-Up and Go (TUG) and the 10m walking speed (WS) are functional tests that have demonstrated associations with global cognition and specific cognitive domains such as processing speed and executive functions in the elderly. However, there is limited understanding regarding their association with cognition in individuals with chronic heart failure (CHF) with reduced or preserved left ventricular ejection fraction (LVEF). Objectives To compare cognition and physical functions in CHF patients with reduced LVEF versus those with mildly reduced or normal LVEF (R-LVEF ≤40% vs N-LVEF >40%). To examine if functional tests predict cognitive performance in each CHF subtype. Methods 42 patients with CHF (66.8±8.1 years old) performed the 6MWT, TUG, and 10m walking test. Neuropsychological tests involved the Montreal Cognitive Assessment (MoCA), the Stroop task and the Rey auditory verbal learning test to assess global cognition, executive functions, processing speed, and episodic memory. LVEF was measured by echocardiography. Results mean LVEF were 32.3±6.9% and 52.6±7.7% for R-LVEF and N-LVEF (p<0.001). Age, education, NYHA class, 6MWT, TUG and WS were similar between groups (p>0.05). After adjusting for age, sex, and education, there was no group difference in the MoCA (23.2±3.9 vs 24.9±3.9 p=0.22 respectively for R-LVEF and N-LVEF). The Stroop inhibition and the Stroop switching task revealed significantly lower performances in R-LVEF vs N-LVEF (81.8±28.7s vs 62.6±13.5s p=0.013 and 89.5±32.8s vs 69.5±14.1s, p=0.016 respectively), as well as fewer words recalled on the fifth repetition of the verbal learning test and the immediate recall (9.2±2.7 vs 11.3±2.3, p=0.020 and 6.2±3.4 vs 8.5±2.6 p=0.013 respectively). Simple linear regressions showed that the 6MWT (R=0.46, p=0.002) and TUG (R= -0.52, p=0.007) significantly predicted MoCA scores in R-LVEF but not in N-LVEF. 6MWT (R= -0.39 p=0.013), TUG (R= 0.47 p=0.016) and WS (R= -0.46 p=0.003) also predicted performances in the Stroop switching condition in R-LVEF only. Conclusion Physical functions are similar between CHF patients with reduced LVEF versus those with mildly reduced or normal LVEF.Global cognition, executive function, and verbal memory (encoding) were lower in CHF with reduced LVEF versus those with mildly reduced/normal LVEF. Functional tests predicted global cognition and executive function in CHF participants with reduced LVEF. Future studies are needed to better understand the pathophysiology of cognitive and physical function deficits in CHF with reduced and preserved LVEF.