Figure 2. End-tidal CO2 pressure (PETCO2) response during incremental exercise test in 4 patients with chronic heart failure of progressive severity. Panel A, A 69-year-old male patient with dilated cardiomyopathy (left ejection fraction: 60%; peak oxygen consumption (VO2): 23.7 mL·kg-1·min-1; VE/VCO2 slope (rest-peak): 33.0). PETCO2 at rest was 29.0 mmHg and change in PETCO2 from rest to the highest value attained during exercise (ΔPETCO2 rest-exercise) was 6.3 mmHg. Panel B, A 58-year-old male patient with ischemic heart failure (left ejection fraction: 42%; peak VO2: 19.0 mL·kg-1·min-1; VE/VCO2 slope (rest-peak): 40.5). PETCO2 at rest was 25.1 mmHg and ΔPETCO2 rest-exercise was 5.8 mmHg. Panel C, A 60-year-old female patient with ischemic heart failure (left ejection fraction: 38%; peak VO2: 13.1 mL·kg-1·min-1; VE/VCO2 slope (rest-peak): 47.1). PETCO2 at rest was 23.0 mmHg and ΔPETCO2 rest-exercise was 5.0 mmHg. Panel D, A 79-year-old female patient with Chagas cardiomyopathy (left ejection fraction: 29%; peak VO2: 10.4 mL·kg-1·min-1; VE/VCO2 slope (rest-peak): 63.8). PETCO2 at rest was 24.9 mmHg and ΔPETCO2 rest-exercise failed to increase.
