Impact of left ventricular ejection fraction on cognitive function in chronic heart failure: insights from key-prognostic CPET parameters

Background Cognitive impairment is a common comorbidity in chronic heart failure patients (CHF) that negatively affects prognosis. Previous studies reported that higher cardiorespiratory fitness (VO2peak), measured with a cardiopulmonary exercise stress test (CPET), is associated with better cognitive performance in CHF. The impact of reduced or preserved left ventricular ejection fraction (LVEF) and the cardiorespiratory parameters during exercise on cognition remain to be studied. Objectives To compare cognition in CHF patients with reduced LVEF versus those with mildly reduced or normal LVEF (R-LVEF ≤40% vs N-LVEF >40%). To examine if key-prognostic CPET parameters predict cognitive performance in each CHF subtype. Methods 68 patients with CHF (67±8 years old) performed a CPET (VO2peak, VE/VCO2 slope, Myers score. All have significant prognostic value). Cognitive assessment included global cognition (Montreal Cognitive Assessment for general cognition; MoCA), processing speed and executive function (Stroop) and memory (Rey auditory verbal learning test). LVEF was measured by echocardiography. Results Mean LVEF were 32.7±6.2% and 52.6±6.8% for R-LVEF and N-LVEF (p<0.001). Age, NYHA class, VO2peak, VE/VCO2 slope, and Myers’ CPET score were similar between groups (p>0.05). After adjusting for age, sex, and education, MoCA scores were not statistically different between groups (23.5±4.6 vs 25.3±2.9 p=0.24 respectively for R-LVEF and N-LVEF). The Stroop switching task revealed a significantly lower performance in R-LVEF vs N-LVEF (89.7±32.1s vs 74.4±16.4s, p=0.028), as well as at the fifth repetition of the verbal learning test (9.3±2.8 vs 11.1±2.2, p=0.015). A trend was observed for the immediate recall on the memory task (6.4±3.5 vs 8.3±3.1 p=0.061). Simple linear regressions showed that VO2peak (mL.kg.min) (R=0.50, p<0.001), VE/VCO2 slope (R=-0.33, p=0.024), and Myers CPET score (R=-0.43, p=0.003) significantly predicted MoCA score in R-LVEF but not in N-LVEF. VO2peak (mL.kg.min) (R= -0.47 p=0.001), VE/VCO2 slope (R= -0.37 p=0.015), and Myers’ CPET score (R= 0.32 p=0.034) predicted Stroop switching performance in R-LVEF only. Conclusion Global cognition, executive function (switching), and verbal memory (encoding) were lower in CHF with reduced LVEF versus those with mildly reduced/normal LVEF despite similar key-prognostic CPET parameters. Key-prognostic CPET parameters predicted global cognition and executive function in CHF participants with reduced LVEF. Future studies are needed to better understand cognitive deficits in CHF and potential intervention to mitigate their impact in patient’s quality of life.