P6185How do peak oxygen consumption, ventilator efficiency slope and end-tidal carbon dioxide partial pressure perform in the short-, long- and very long-term risk stratification in heart failure?

Abstract

Aims: Peak oxygen consumption (pVO2), ventilatory efficiency (VE/VCO2) slope and end-tidal carbon dioxide partial pressure (PETCO2) are recommended for risk stratification in heart failure (HF), but data on the very long-term performance of these parameters is limited. We aimed to evaluate their power to predict adverse events in the short-, long- and very long-term follow-up (FUP). Methods: We included patients of a single center with HF with left ventricular ejection fraction ≤40%, in NYHA class II-III, who underwent a cardiopulmonary exercise testing (CPET) with achievement of the anaerobic threshold (AT). The VE/VCO2 slope was calculated using data of the whole exercise. The PETCO2 was calculated at baseline (baseline PETCO2) and at the AT (AT PETCO2). All patients were followed for 60 months. The combined endpoint, which was defined as cardiac death, urgent heart transplantation or need for mechanical circulatory support, was analysed at 12, 36 and 60 months of FUP. Results: In the 263 enrolled patients, 75% male with mean age 54 (SD=12) years, the mean (SD) pVO2, VE/VCO2 slope, baseline PETCO2 and AT PETCO2 were 20.0 (5.3) mL/kg/min, 31.3 (7.4), 33.0 (4.5) mmHg and 36.8 (6.0) mmHg, respectively. The Table and Figure present the discriminative power of each parameter. Conclusions: The pVO2, VE/VCO2 slope, baseline and AT PETCO2 were predictors of adverse events in the short-, long- and very long-term FUP. VE/VCO2 slope was the most accurate predictor, consistently over time. Conversely to VE/VCO2 and AT PETCO2, the AUC of pVO2 and baseline PETCO2 declined significantly from 12 to 36 months; from 36 to 60 months the AUC remained stable for all parameters. Except for selected cases, frequent reassessment by CPET may not be necessary for many stable HF patients, as it may suffice in the very long-term risk stratification.