Performance of Heart Failure Patients with Severely Reduced Ejection Fraction during Cardiopulmonary Exercise Testing on Treadmill and Cycle Ergometer; Similarities and Differences

Background: Peak oxygen consumption (VO 2 ) measured by cardiopulmonary exercise testing (CPET) is a significant predictor of mortality and future transplantation in heart failure patients with severely reduced ejection fraction (HFrEF). The present study evaluated the differences in peak VO 2 and other prognostic variables between treadmill and cycle CPETs in these patients. Methods: In this cross-over study design, thirty males with severe HFrEF underwent CPET on both a treadmill and a cycle ergometer within 2–5 days apart, and important CPET parameters between two exercise test modalities were compared. Results: Peak VO 2 was 23.12% higher on the treadmill than on cycle (20.55 ± 3.3 vs. 16.69 ± 3.01, p < 0.001, respectively). Minute ventilation to carbon dioxide production (VE/VCO 2 ) slope was not different between the two CPET modes ( p = 0.32). There was a strong positive correlation between the VE/VCO 2 slopes during treadmill and cycle testing (r = 0.79; p < 0.001). VE/VCO 2 slope was not related to peak respiratory exchange ratio (RER) in either modality (treadmill, r = 0.13, p = 0.48; cycle, r = 0.25, p = 0.17). The RER level was significantly higher on the cycle ergometer ( p < 0.001). Conclusion: Peak VO 2 is higher on treadmill than on cycle ergometer in severe HFrEF patients. In addition, VE/VCO 2 slope is not a modality dependent parameter and is not related to the patients’ effort during CPET.