Type of exercise alters VE/VCO2slope in CAD patients

The exercise carbon dioxide equivalent slope predicts prognosis in coronary artery disease patients. However, no study examined whether the carbon dioxide equivalent slope in coronary artery disease patients is dependent on the type of exercise. Twenty-nine coronary artery disease patients performed maximal cardiopulmonary exercise tests on bike, treadmill and arm cycle, with assessment of oxygen uptake, carbon dioxide output, and expiratory volume. The carbon dioxide equivalent slope was calculated from rest till peak exercise. The carbon dioxide equivalent slope was significantly different between walking, cycling, and arm cranking exercises (P<0.05), i.e. the carbon dioxide equivalent slope was the lowest during walking and the highest during arm cranking. Bland-Altman plots revealed that the difference of the carbon dioxide equivalent slope between exercises was greater in the case of a higher averaged carbon dioxide equivalent slope and overall peak oxygen uptake. In conclusion, the carbon dioxide equivalent slope is significantly dependent on the type of exercise in coronary artery disease patients. Additionally, the averaged carbon dioxide equivalent slope and peak oxygen uptake affect the difference of the carbon dioxide equivalent slopes between exercises.