Objective:

To investigate the relative contributions of central hemodynamics, ventilatory efficiency, and peripheral muscle function to exercise capacity in patients with heart failure with preserved ejection fraction (HFpEF).

Approach:

• Study Design: Cross-sectional analysis using baseline data from the HIT-HF trial.
• Assessment Methods: V˙O2peak and ventilatory efficiency assessed via cardiopulmonary exercise testing; stroke volume measured by impedance cardiography; heart rate via electrocardiography; total hemoglobin mass by carbon monoxide rebreathing; muscle oxygen saturation by near-infr…
• Statistical Analysis: Multivariable linear regression adjusted for age, sex, and body fat mass; missing data handled by multiple imputations.

Key Findings:

• Leg power had the strongest positive association with relative V˙O2peak (β = 0.35, 95% CI: −0.20 to 0.89).
• Leg fat-free mass showed the strongest association with absolute V˙O2peak (β = 0.57, 95% CI: 0.21–0.92).
• Stroke volume and heart rate had smaller associations with exercise capacity.
• SmO2, tHbmass, and ventilatory efficiency showed trivial associations with V˙O2peak (β between −0.1 and 0.1).

Interpretation:

In HFpEF, peripheral muscle function is more strongly associated with exercise capacity than central hemodynamics or ventilatory efficiency.

Limitations:

• Small sample size (46 patients, 43 included in analysis).
• Cross-sectional design limits causal inferences.

Conclusion:

Peripheral muscle function is a critical determinant of exercise capacity in patients with HFpEF.