Effect of heart failure and atrial fibrillation on cardiorespiratory fitness in hemodialysis patients

Objective: Heart failure (HF) and atrial fibrillation (AF) are highly prevalent in hemodialysis. They are well-known significant modifiers of the disease associations with cardiovascular outcomes, but there is a lack of evidence regarding the effects of HF and AF on cardiorespiratory fitness. This study is the first to examine the possible association of the presence of HF and AF with exercise intolerance in patients undergoing hemodialysis. Design and method: This analysis included 40 sex- and age-matched participants [10 hemodialysis patients with HF or AF, 10 hemodialysis patients without HF or AF, 10 patients with HF or AF without chronic kidney disease (CKD) and 10 healthy controls) that underwent CPET and spirometry examinations. Results: VO2peak (ml/min/kg) showed a graded increase between hemodialysis patients with HF or AF, hemodialysis patients without HF or AF, non-CKD patients with HF or AF and controls (13.17±2.45 vs 15.26±3.29 vs 19.64±5.84 vs 25.11±6.94 ml/min/kg, p<0.001); VO2peak (ml/min) followed the same pattern (1172±197 vs 1269±314 vs 1817±583 vs 1952±592 ml/min respectively, p=0.001). VO2peak (%predicted), VO2AT (ml/kg/min), VO2AT (ml/min) and maximal work load significantly differ between the study groups, with a tendency for higher values from hemodialysis patients to non-CKD patients with HF or AF and to healthy controls. FEV1 and FVC levels were similar between the study groups. In the whole population, VO2peak (ml/kg/min) showed a positive correlation with hemoglobin (r=0.663, p<0.001) and negative correlations with high-sensitivity cardiac troponin I (r=-0.493, p=0.001) and BNP (r=-0.479, p=0.002). Conclusions: Hemodialysis patients have low exercise tolerance, and the presence of HF or AF is associated with further decreased values of VO2peak, the most important determinant of cardiorespiratory fitness.