Relationship between ventilatory expired gas and cardiac parameters during symptom-limited exercise testing in patients with heart failure

PURPOSE: This study investigates the relationship between ventilatory expired gas and cardiac parameters measured during exercise testing in patients with heart failure. METHODS: Twenty-five subjects (12 male, 13 female) diagnosed with compensated heart failure underwent symptom-limited exercise testing with ventilatory expired gas analysis. Metabolic and cardiac measures of interest were collected during testing. RESULTS: Mean peak oxygen consumption (VO₂), minute ventilation/carbon dioxide production (V_E/VCO₂) slope, percentage of age predicted maximal heart rate achieved during exercise testing (%APMHR), and peak respiratory exchange ratio were 14.7 ± 4.7 mL O₂/kg/min^-1, 33.8 ± 9.8, 76% ± 15%, and 1.1 ± 0.11, respectively. The V_E/VCO₂ slope was significantly correlated with the following: %APMHR (r = -0.81, P < 0.001), peak VO₂ (r = -0.83, P < 0.001), VO₂ at ventilatory threshold (r = -0.70, P < 0.001), and the dead space to tidal volume ratio (V_DV_t) (r = 0.65, P < 0.001). The ability of peak VO₂ and %APMHR to predict the V_E/VCO₂ slope was significant (r = 0.86, r² = 0.72, P < 0.0001). CONCLUSION: This study demonstrates the importance of analyzing multiple exercise test parameters, including metabolic measures, in patients with heart failure.