Abstract
INTRODUCTION: The minute ventilation carbon dioxide production (VE/VCO2) slope is a consistent and robust prognostic marker in the heart failure (HF) population. The purpose of this study was to assess the ability of the newly developed ventilatory classification system, a powerful predictor of major cardiac events (mortality, transplantation, and left ventricular assist device implantation), to identify varying degrees of risk for cardiac-related hospitalization.
METHODS: A total of 459 patients with chronic HF who underwent cardiopulmonary exercise testing were included in this analysis. The VE/VCO2 slope was determined, and participants were classified into 1 of 4 groups (ventilatory class [VC]-I: <=29.9; VC-II: 30.0-35.9; VC-III: 36.0-44.9; and VC-IV: >=45.0). Participants were tracked for cardiac-related hospitalization for 2 years following testing.
RESULTS: There were 169 cardiac-related hospitalizations during the 2-year tracking period (annual event rate = 21.6%). Decompensated HF, cardiac ischemia, and cardiac arrhythmia were the reasons for hospitalization in 83%, 11%, and 6% of the cases, respectively. Kaplan-Meier analysis revealed that the VC system was prognostically significant (log-rank = 85.2, P < .001) and superior to the Weber classification system (log-rank = 70.0, P < .001).
DISCUSSION: This study indicates that the VC system, based on the VE/VCO2 slope, effectively identifies patients with HF at varying degrees of risk for cardiac-related hospitalization. Furthermore, this newly developed system prognostically outperformed the established Weber classification system based on peak oxygen uptake.