Fig. 3

Kaplan–Meier survival curves for patients stratified into two groups on the basis of the threshold value for PETCO₂ at peak exercise determined from ROC analysis: Patients with a PETCO₂ at peak exercise ≥30.9 mmHg (n = 56) and those with a PETCO₂ at peak exercise <30.9 mmHg (n = 22). The survival rate in the patients with a lower PETCO₂ at peak exercise was significantly lower than that seen in those with a higher PETCO₂ at peak exercise (P < 0.0001)