Abstract 16798: The Influence of Heart Failure With Preserved or Reduced Ejection Fraction on Relationships Between Cardiac Power and Stroke Work With VO2
Introduction: Invasive measurement of cardiac power (CP) and stroke work (SW) during exercise are robust indices of cardiac function and relate to syndrome severity and prognosis in heart failure patients with preserved (HFpEF) or reduced (HFrEF) ejection fraction. Because invasive measurement via catheterization laboratories are not always readily available, non-invasive cardiopulmonary exercise testing to estimate cardiac function is routinely performed in the clinical evaluation of HFpEF and HFrEF. However, it is unknown how VO2 relates with CP and SW in HFpEF vs HFrEF. We compared relationships between CP and SW with VO2 at rest and peak exercise in HFpEF vs HFrEF.
Methods: 30 HFpEF and 32 HFrEF (EF: 62±2 vs 22±1%; males: 17 vs 30; age: 70±2 vs 55±2 yrs; BMI: 34±1 vs 28±1 kg/m2; wt: 98±4 vs 86±3 kg (all p<0.05)) participated in exercise testing during right heart catheterization. Oxygen consumption (VO2) was measured continuously from rest to peak work. Invasive measures at rest and peak work included mean radial arterial pressure (MAP), right atrial pressure (RAP), and pulmonary capillary wedge pressure (PCWP). We calculated CP=(MAP–RAP) x QI x 2.22х10-3 and SW=(MAP–PCWP) x SVI x 0.133.
Results: At rest, R2 between VO2 and CP or SW were not different between HFpEF (CP=0.41, SW=0.30) and HFrEF (CP=0.39, SW=0.15). Slopes did not differ significantly between HFpEF (CP=0.13, SW=0.01) and HFrEF (CP=0.16, SW=0.01) for regressions between VO2 and CP or SW; but, fitted intercepts of the regression showed significantly higher intercepts in HFrEF (CP=0.89, SW=1.16) vs HFpEF (CP=0.05, SW=0.27) for VO2 vs CP and SW, respectively. At peak exercise, R2 between VO2 and CP or SW were not different between HFpEF (CP=0.48, SW=0.64) and HFrEF (CP=0.70, SW=0.67). Slopes did not differ between HFpEF (CP=0.18, SW=0.02) and HFrEF (CP=0.15, SW=0.02) for regressions between VO2 and CP or SW, whereas the fitted intercepts the slope of the regression were significantly higher in HFrEF (CP=5.1, SW=4.4) vs HFpEF (CP=3.2, SW=2.0) for VO2 vs CP and SW, respectively.
Conclusion: Our data suggest that despite lower VO2 relative to CP and SW in HFpEF, both the strength of relationship and rate of increase in VO2 relative to CP and SW are similar between HFpEF and HFrEF at rest and peak exercise.
Author Disclosures: E.H. Van Iterson: None. E.M. Snyder: None. B.A. Borlaug: None. T.P. Olson: None.
- © 2015 by American Heart Association, Inc.