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.