Abstract 16287: The Calibration of Oxygen Uptake, Delivery, and Utilization is Influenced by Heart Failure With Preserved versus Reduced Ejection Fraction During Exercise
Introduction: Patients with heart failure with preserved (HFpEF) or reduced (HFrEF) ejection fraction demonstrate low oxygen uptake (VO2) and cardiac output (Q) during cardiopulmonary exercise testing (CPET). Relationships between VO2 and Q with both O2 delivery (DO2) and O2 utilization remain unclear across the HF spectrum. We hypothesized that compared to HFpEF, HFrEF patients demonstrate impaired mechanisms of O2 uptake, delivery, and utilization during submaximal exercise at matched external workload (20W).
Methods: HFpEF and HFrEF [N = 30 vs 21; EF; 61 ± 3 vs 22 ± 4 %; males: 17 vs 20; age: 71 ± 4 vs 56 ± 4 yrs; BSA: 2.14 ± 0.1 vs 2.06 ± 0.12 m2; means ± 95% CL] performed CPET. VO2 was measured breath-by-breath. Q indexed to BSA (QI) was measured via the direct Fick method. We calculated arterial oxygen content, CaO2 = (1.34 x Hb x SaO2) + (0.0031 x PaO2); DO2 = (CaO2 x QI x 10); VO2 index, VO2I = AVO2 x QI x 10; O2 utilization coefficient (OUC) = VO2I/DO2. Between group comparisons were adjusted for sex and age.
Results: There were no between group differences at rest (Figure). At 20W, VO2 (0.63 ± 0.05 vs 0.45 ± 0.07 L/min), VO2I (299 ± 25 vs 231 ± 31 mL/min/m2), and OUC (0.62 ± 0.04 vs 0.53 ± 0.05) were higher in HFpEF than HFrEF, respectively. There were no between group differences for QI, CaO2, AVO2, and DO2.
Conclusion: These data suggest that HFpEF and HFrEF patients demonstrate similar deficits in systemic O2 transfer and extraction during exercise. Despite similar DO2 and AVO2 across HF, VO2I is higher in HFpEF in the transition from rest to low workloads. This suggests HFpEF demonstrate a higher metabolic cost of work compared to HFrEF. Additional mechanistic studies examining systemic O2 utilization are warranted to understand this disconnect between VO2I with DO2 and AVO2 in HFpEF compared to HFrEF.
- Heart failure, adult
- Diastolic function
- Cardiopulmonary exercise testing
- Oxygen uptake
- Expired gas analysis
Author Disclosures: E.H. Van Iterson: None. B.A. Borlaug: None. B.D. Johnson: None. T.P. Olson: None.
- © 2016 by American Heart Association, Inc.