Prognostic value of end-tidal CO2 pressure during exercise in patients with left ventricular dysfunction

Abstract

We compared the prognostic power of end-tidal CO2 pressure (PETCO2) during exercise, an index of arterial CO2 pressure, with those of established respiratory gas indexes during exercise testing in patients with left ventricular dysfunction. Seventy-eight consecutive patients with a left ventricular ejection fraction (LVEF) ≤40% were enrolled in the study. All the patients performed a symptom-limited incremental exercise test with respiratory gas measurements. PETCO2 at peak exercise, peak O2 uptake (VO2), the ratio of the increase in ventilation to the increase in CO2 output (VE/VCO2 slope), and the ratio of the increase in VO2 to the increase in work rate (ΔVO2/ΔWR) were measured. PETCO2 at peak exercise was significantly correlated with peak VO2, VE/VCO 2 slope and ΔVO2/ΔWR. During a prospective follow-up period of 992 ± 570 days, 14 cardiac deaths occurred. As compared to survivors, non-survivors had a significantly lower LVEF, lower PETCO2 at peak exercise, lower peak VO2, lower ΔVO2/ΔWR and a higher VE/VCO2 slope. Among these indexes, only PETCO2 at peak exercise was found to be an independent predictor for cardiac death. PETCO2 at peak exercise is useful in predicting poor prognosis in patients with left ventricular systolic dysfunction. © 2008 The Physiological Society of Japan and Springer.