Author(s): SCHOCH, R., KRÖPFL, J., GASSER, B., DIETERLE, T., SCHMIDT-TRUCKSÄSS, A., Institution: UNIVERSITY OF BASEL, Country: SWITZERLAND, Abstract-ID: 2462

INTRODUCTION:
Patients with heart failure with preserved ejection fraction (HFpEF) are commonly characterized by impaired exercise capacity, typically assessed through cardiopulmonary exercise testing. A key parameter in this assessment is maximal oxygen consumption (V̇O2peak), derived from the product of cardiac output (CO) and arterio-venous oxygen difference (a-vDO2). The ability to evaluate CO non-invasively during exercise enables the calculation of a-vDO2, thus providing comprehensive insights in circulatory function during cardiopulmonary exercise testing. This study aims to clarify the determinants contributing to reduced exercise capacity in patients with HFpEF.
METHODS:
Forty patients with HFpEF underwent cardiopulmonary exercise testing. Gas exchange parameters were assessed via breath-by-breath analysis (MetaMax 2B, Cortex Biophysik GmbH, Leipzig, Germany), while CO was measured using Physioflow® (Manatec Biomedical, Poisy, France) and a-vDO2 was subsequently calculated. Patients were stratified into two groups based on the median of absolute V̇O2peak for further analysis.
RESULTS:
Median of V̇O2peak was 1.50L/min. Group with patients with lower exercise capacity (<1.50 L/min) demonstrated lower CO (12.67(3.07) vs. 14.99(3.26) L/min, p=0.032), and lower stroke volume (92.1(23.5) vs. 107.2(18.0) mL, p=0.036), compared to the other group. However, there were no significant differences observed in age (73(10) vs. 69(11) years, p=0.233), BMI (24.8(4.9) vs. 27.8(5.3) kg/m2, p=0.068), a-vDO2 (11.0(3.5) vs. 12.8(3.3) mL/100mL, p=0.131), peak heart rate (139(17) vs. 145(19) bpm, p=0.306), or respiratory exchange ratio (1.06(0.06) vs 1.05(0.04), p=0.303).
CONCLUSION:
The associations between reduced exercise capacity, lower cardiac output, and stroke volume among patients with HFpEF indicate an inability to increase stroke volume via the Frank-Starling mechanism while chronotropic incompetence or peripheral vascular dysfunction may not be as decisive as discussed elsewhere. These findings underline the potential utility of targeted exercise interventions aimed at improving cardiac function to increase exercise tolerance in patients with HFpEF.