Association between left ventricular global longitudinal strain, functional capacity and quality of life in patients with chronic kidney disease

Background: Patients with Chronic Kidney Disease (CKD) have a significant burden of dyspnoea and fatigue in spite of having normal left ventricular (LV) ejection fraction (EF). Global longitudinal strain (GLS) can detect subtle changes in LV function. This study aimed to evaluate the relationship between LV function, quality of life (QOL) and functional capacity in CKD. Methods: A cross sectional study of patients with CKD stages 3 and 4 (n=136). Clinical characteristics, biochemical data, functional capacity [6 minute walk test (6MWT), timed up and go (TUG) test] and QOL [Short Form-12 (SF-12v2™)] were measured. Echocardiography was used to assess GLS, EF and diastolic function (E/e’). Associations between QOL, functional capacity and cardiac function were evaluated. Results: The mean age was 59.4±9.8 years, 58.1% were male, estimated Glomerular Filtration Rate (eGFR) was 44.4±10.1 ml/min/1.73m2, GLS was -18.3±3.6% and EF was 65.8±7.7%. Average 6MWT was 474.6±105.4m and TUG test was 5.3±1.5s. GLS and E/e’ correlated with distance walked in 6MWT [GLS(r=-0.22, p=0.01); E/e’(r=-0.38, p=0.006)] and time for TUG test [GLS(r=0.19, p=0.04); E/e’(r=0.29, p=0.001)]. Following adjustment for potential confounders, GLS remained independently associated with 6MWT(Model R2=0.37, p<0.001). Mean physical component summary scores (PCS) and mental component summary scores (MCS) using SF-12v2™ were 42.5±10.2 and 51.0±9.6. There was no cardiac parameter that was independently associated with PCS. However older age and worse GLS was associated with lower MCS (Model R2=0.21, p<0.001). Conclusion: GLS may be sensitive marker to detect early changes in effort tolerance and QOL related to LV dysfunction.