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

We compared the prognostic power of end-tidal CO(2) pressure (PETCO(2)) during exercise, an index of arterial CO(2) 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) <or=40% were enrolled in the study. All the patients performed a symptom-limited incremental exercise test with respiratory gas measurements. PETCO(2) at peak exercise, peak O(2) uptake (VO(2)), the ratio of the increase in ventilation to the increase in CO(2) output (VE/VCO(2) slope), and the ratio of the increase in VO(2) to the increase in work rate (deltaVO(2)/deltaWR) were measured. PETCO(2) at peak exercise was significantly correlated with peak VO(2), VE/VCO(2) slope and deltaVO(2)/deltaWR. 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 PETCO(2) at peak exercise, lower peak VO(2), lower deltaVO(2)/deltaWR and a higher VE/VCO(2) slope. Among these indexes, only PETCO(2) at peak exercise was found to be an independent predictor for cardiac death. PETCO(2) at peak exercise is useful in predicting poor prognosis in patients with left ventricular systolic dysfunction.