Exercise stress testing recovery kinetics: the forgotten phase

Abstract Background Impaired exercise capacity is a cardinal feature of heart failure (HF). Peak oxygen uptake (pVO2) and ventilatory efficiency (VE/VCO2 slope) during exercise are well-consolidated prognostic markers in patients with HF. A previous study suggested that abnormally prolonged VO2 recovery, specifically the failure to decrease VO2 from peak exercise by 10.5 mL/kg/min at 180 seconds of the recovery phase, predicts adverse outcomes in HF. However, it is unknown to what extent the recovery of VEqCO2, a marker of ventilation/perfusion mismatch, adds prognostic value to the already existing parameters. Purpose The aim of this study was to characterize the functional and prognostic significance of VEqCO2 kinetics following peak exercise in individuals with HF. Methods This retrospective single-center study included consecutive adult patients with chronic (>3 months) and stable HF with left ventricular ejection fraction (LVEF) 1) at 180 seconds, were significantly older (p=0.02), had a lower LVEF (p