VAN Iterson EH, Olson TP, Borlaug BA, Johnson BD, Snyder EM.

Med Sci Sports Exerc. 2017 Sep;49(9):1758-1768

INTRODUCTION: Cardiopulmonary exercise testing (CPET) plays an important role in
properly phenotyping signs and symptoms of heart failure with preserved ejection
fraction (HFpEF). The prognostic value of CPET is strengthened when accompanied
by cardiac hemodynamic measurements. Although recognized as the “gold” standard,
cardiac catheterization is impractical for routine CPET. Thus, advancing the
scientific/methodologic understanding of noninvasive techniques for exercise
cardiac hemodynamic assessment is clinically impactful in HFpEF. This study
tested the concurrent validity of noninvasive acetylene gas (C2H2) uptake,
echocardiography (ECHO), and oxygen pulse (O2pulse) for measuring/predicting
exercise stroke volume (SV) in HFpEF.
METHODS: Eighteen white HFpEF and 18 age-/sex-matched healthy controls
participated in upright CPET (ages, 69 ± 9 yr vs 63 ± 9 yr). At rest, 20 W, and
peak exercise, SV was measured at steady-state via C2H2 rebreathe (SVACET) and
ECHO (SVECHO), whereas O2pulse was derived (=V˙O2/HR).
RESULTS: Resting relationships between SVACET and SVECHO, SVECHO and O2pulse, or
SVACET and O2pulse were significant in HFpEF (R = 0.30, 0.36, 0.67), but not
controls (R = 0.07, 0.01, 0.09), respectively. Resting relationships persisted to
20 W in HFpEF (R = 0.70, 0.53, 0.70) and controls (R = 0.05, 0.07, 0.21),
respectively. Peak exercise relationships were significant in HFpEF (R = 0.62,
0.24, 0.64), but only for SVACET versus O2pulse in controls (R = 0.07, 0.04,
0.33), respectively. Standardized standard error of estimate between techniques
was strongest in HFpEF at 20 W: SVACET versus SVECHO = 0.57 ± 0.22; SVECHO versus
O2pulse = 0.71 ± 0.28; SVACET versus O2pulse = 0.56 ± 0.22.
CONCLUSIONS: Constituting a clinically impactful step towards construct
validation testing, these data suggest SVACET, SVECHO, and O2pulse demonstrate
moderate-to-strong concurrent validity for measuring/predicting exercise SV in
HFpEF.