The partial pressure of resting end-tidal carbon dioxide predicts major cardiac events in patients with systolic heart failure

Background: The resting partial pressure of end-tidal carbon dioxide (Petco₂) has been shown to reflect cardiac performance in acute care settings in patients with heart failure (HF). The purpose of the present study was to compare the prognostic ability of the partial pressure of Petco₂ at rest to other commonly collected resting variables in patients with systolic HF. Methods: A total of 353 patients (mean age 58.6 ± 13.7, 72% male) with systolic HF were included in this study. All patients underwent cardiopulmonary exercise testing where New York Heart Association (NYHA) class, resting Petco₂, peak oxygen consumption, and the minute ventilation/carbon dioxide production slope were determined. Subjects were then followed for major cardiac events (mortality, left ventricular assist device implantation implantation, urgent heart transplantation). Results: There were 104 major cardiac events during the 23.6 ± 17.0-month tracking period. Multivariate Cox regression analysis revealed NYHA class (χ² 28.7, P <.001), left ventricular ejection fraction (residual χ² 21.7, P <.001), and resting Petco₂ (residual χ² 14.1, P <.001) were all prognostically significant and retained in the regression. In a separate Cox regression analysis, left ventricular ejection fraction (residual χ² 8.8, P = .003), NYHA class (residual χ² 7.7, P = .005), and resting Petco₂ (residual χ² 5.7, P = .02) added prognostic value to the minute ventilation/carbon dioxide production slope (χ² 26.0, P <.001). Conclusion: Resting Petco₂ can be noninvasively collected from subjects in a short period, at a low cost, and with no risk or discomfort to the patient. Given the prognostic value demonstrated in the present study, the clinical assessment of resting Petco₂ in the HF population may be warranted.