Cardiopulmonary exercise testing is a prognostic tool in heart failure with reduced left ventricular ejection fraction (HFrEF). Prognosticating algorithms have been proposed, but none has been validated. In 2017, a predictive algorithm, based on peak oxygen consumption (VO2), ventilatory response to exercise (ventilation [VE] carbon dioxide production [VCO2], the VE/VCO2 slope), exertional oscillatory ventilation (EOV), and peak respiratory exchange ratio, was recommended, according treatment with β blockers: patients with HFrEF registered in the metabolic exercise test data combined with cardiac and kidney indexes (MECKIs) database were used to validated this algorithm. According to the inclusion/exclusion criteria, 4,683 MECKI patients with HFrEF were enrolled. At 3 years follow-up, the end point was cardiovascular death and urgent heart transplantation (cardiovascular events [CV]). CV events occurred in 25% in patients without β blockers, whereas those with β-blockers had 11% (p <0.0001). In patients without β blockers, 36%, 24%, and 7% CV events were observed in those with peak VO2 ≤10, with peak VO2 >10 <18, and with peak VO2 ≥18 ml/kg/min (p = 0.0001), respectively; in MECKI patients with peak VO2 ≤10 and patients with intermediate exercise capacity, a peak respiratory exchange ratio (≥1.15) and VE/VCO2 slope (≥35) were diriment, respectively (p = 0.0001). EOV, when occurred, increased risk. In MECKI patients on β blockers, 29%, 17%, and 8% CV events were noticed in those with a peak VO2 ≤8, with peak VO2 = 8 to 12, and patients with peak VO2 ≥12 ml/kg/min, respectively (p = 0.0000); when EOV was monitored an increment of risk was witnessed. In conclusion, the outcome of this algorithm was confirmed with the MECKI cohort.
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