Carbon dioxide elimination pattern at cardiopulmonary exercise testing in patients with low ejection fraction value
The objective of this study was to evaluate partial pressure of end tidal carbon dioxide (Petm<sub>2</sub>) over time on exertion (E) and its predictive value in evaluation of risk of unfavorable outcome in patients with low ejection fraction (EF) value. Methods. Patients (n = 53) with pronounced chronic heart failure (CHF), included in heart transplantation waiting list, were enrolled in the prospective study. All patients underwent cardiopulmonary exercise testing (CPET). Mortality or INCOR left ventricle bypass system implantation according to vital indications within 1 year of follow-up were evaluated as an end-point. Results. Patients with CHF and low EF were characterized by low parameters of E tolerance and peak oxygen consumption (10.4 (9.6-11.7) ml/min/kg). The average Petm<sub>2</sub> level by group was 30.4 (28.3-33.0) mm Hg; in 32% of patients this value decreased or did not change in CPET compared with that in resting state. The significant relationship between increased risk of unfavorable outcome within 1 year of follow-up with low baseline PetCo<sub>2</sub> value (odds ratio (OR) - 0.22 (0.05-0.87);p = 0.020) and absence of its increment in PE (OR - 0.16 (0.10-0.54); p = 0.009) was observed. Conclusion. The significant predictive factors of unfavorable outcome within 1 year of follow-up in patients with pronounced CHF and low EF include PetCO2 value in resting state, as well as PetCO2 change over time after E challenge.