Prognostic value of VE/VCO₂ slope in overweight heart failure patients

A decreased hypercapnic ventilatory response of the overweight patients would lower the ventilation equivalent of carbon dioxide (VE/VCO₂) slope but worsen prognosis. The aim of this study was to compare the prognostic ability of the VE/VCO₂ slope and peak oxygen consumption (pVO₂) between normal and overweight heart failure (HF) patients.

Prospective evaluation of ambulatory patients with reduced left ventricular ejection fraction who underwent baseline assessment with a cardiopulmonary exercise test. The primary endpoint was cardiac death or urgent heart transplantation in the 5-year period of follow-up. The predictive power of VE/VCO₂ slope and pVO₂ were compared (area under the curve (AUC) analysis and Hanley & McNeil test), in the subgroups of patients with body mass index (BMI) of 18.5-24.9 kg/m² and ≥ 25 kg/m². Statistical differences with a p value < 0.05 were considered significant.

There were 270 enrolled patients, with a mean BMI of 27 ± 4 kg/m². No differences between normal and overweight patients (38.0% vs 29.8%, P=0.170) were found during the 5-year period for the primary endpoint. The VE/VCO₂ slope was non-inferior to pVO₂ in both groups at 1, 3 and 5 years of follow-up. The comparison of VE/VCO₂ slope between groups revealed a significant lower AUC at 3 (0.921 vs 0.787, P=0.022) and 5 years (0.898 vs 0.787, P=0.044) of follow-up for overweight patients.

Despite VE/VCO₂ slope provides a discriminative power at least as good as pVO₂ for predicting adverse events in both normal and overweight HF patients, a significant lower predictive power was found in overweight patients.