Impaired Renal Function Reduces the Anaerobic Threshold in Patients with Chronic Heart Failure

Abstract

Objective: Chronic kidney disease is associated with poor prognosis in patients with chronic heart failure (CHF). Anaerobic threshold (AT) is a useful index to predict prognosis of patients with CHF. In the present study, we investigated the relation between the impaired kidney function and the anaerobic threshold in patients with CHF. Methods: We enrolled 71 consecutive patients with CHF (59±11 years-old). We estimated glomerular filtration rate (GFR) by MDRD formula, and diagnosed impaired renal function as estimated GFR <60ml/min. We performed cardiopulmonary exercise test to measure AT, and to determine VO2 at AT and VE-VO2 slope. We measured left atrium diameter (LAD), left ventricular ejection fraction (LVEF), end-diastolic and systolic left ventricular diameter (LVDd and LVDs), mitral annular velocity (e'), and E/e' ratio on echocardiography. Results: Impaired renal function was diagnosed in 53 (75%) patients, and they had lower AT value(9.8±1.7 vs. 11.0±2.0 ml/kg/min, p=0.023) and tended to show steeper VE/VCO2 slope(36.4±10.6 vs.30.9±2.3, p=0.053) than those with preserved function. On echocardiography, E/e' was significantly higher in patients with impaired function (20.8±13.6 vs.12.1±4.6, p=0.007), while no differences were observed in LVEF, LVDd, LVDs and LAD between two groups. Conclusion: CHF patients with impaired renal function had significant low AT value and higher left ventricular end diastolic filling pressure. Renal dysfunction reduces the exercise capacity for CHF patients and impairs left ventricular diastolic function.