Renal function and peak exercise oxygen consumption in chronic heart failure with reduced left ventricular ejection fraction

Background: Chronic kidney disease is associated with sympathetic activation and muscle abnormalities, which may contribute to decreased exercise capacity. We investigated the correlation of renal function with peak exercise oxygen consumption (V˙O2) in heart failure (HF) patients. Methods and Results: We recruited 2,938 systolic HF patients who underwent clinical, laboratory, echocardiographic and cardiopulmonary exercise testing. The patients were stratified according to estimated glomerular filtration rate (eGFR). Mean follow-up was 3.7 years. The primary outcome was a composite of cardiovascular death and urgent heart transplantation at 3 years. On multivariable regression, eGFR was predictor of peakV˙O2 (P<0.0001). Other predictors were age, sex, body mass index, HF etiology, NYHA class, atrial fibrillation, resting heart rate, Btype natriuretic peptide, hemoglobin, and treatment. After adjusting for significant covariates, the hazard ratio for primary outcome associated with peakVO2 <12 ml ・ kg−1 ・ min−1 was 1.75 (95% confidence interval (CI): 1.06–2.91; P=0.0292) in patients with eGFR ≥60, 1.77 (0.87–3.61; P=0.1141) in those with eGFR of 45–59, and 2.72 (1.01– 7.37; P=0.0489) in those with eGFR <45 ml ・ min−1 ・ 1.73 m−2. The area under the receiver-operating characteristic curve for peakV˙O2 <12 ml ・ kg−1 ・ min−1 was 0.63 (95% CI: 0.54–0.71), 0.67 (0.56–0.78), and 0.57 (0.47–0.69), respectively. Testing for interaction was not significant. Conclusions: Renal dysfunction is correlated with peakV O2. A peakV O2 cutoff of 12 ml ・ kg–1 ・ min–1 offers limited prognostic information in HF patients with more severely impaired renal function.