Ventilatory Expired Gas at Constant-Rate Low-Intensity Exercise Predicts Adverse Events and is Related to Neurohormonal Markers in Patients With Heart Failure

BackgroundVentilatory efficiency (VE/VCO2 ratio) and the partial pressure of end-tidal carbon dioxide (PETCO2), obtained during moderate to high levels of physical exertion demonstrate prognostic value in heart failure (HF). The present investigation assesses the clinical utility of these variables during low-intensity exercise.Methods and ResultsOne hundred and thirty subjects diagnosed with HF underwent a 2-minute, constant-rate treadmill session at 2 miles per hour. Both the VE/VCO2 ratio and PETCO2 were recorded during exercise (30-second average) and their change (Δ) from rest. B-type and atrial natriuretic peptide (BNP and ANP) were also determined. Only PETCO2 and ΔPETCO2 emerged from the multivariate Cox regression. Receiver operating characteristic curve analysis revealed the prognostic classification schemes were significant with thresholds of