Cardiac output changes during exercise in heart failure patients: focus on mid-exercise

Area of Science:

• Cardiology
• Exercise Physiology
• Heart Failure Research

Background:

• Peak exercise oxygen uptake (VO2) and cardiac output (CO) are key prognostic indicators in heart failure (HF).
• However, these peak measures do not reflect real-life physical activity, which involves submaximal exertion.

Purpose of the Study:

• To investigate the predictive value of mid-exercise VO2 and CO for peak exercise capacity in HF patients.
• To determine if mid-exercise parameters can identify patients with severe HF.

Main Methods:

• Maximal cardiopulmonary exercise tests were conducted on 231 HF patients and 265 healthy volunteers.
• Non-invasive CO measurements were taken at rest, mid-exercise, and peak exercise using inert gas rebreathing.
• HF patients were stratified into two groups based on peak VO2 (<50% and ≥50% predicted), and data were adjusted for age, gender, and BMI.

Main Results:

• HF patients, particularly those with lower peak VO2 (Group 1), exhibited lower mid-exercise VO2, CO, and stroke volume (SV) compared to Group 2 and healthy subjects.
• The increase in SV from rest to mid-exercise was significantly lower in Group 1.
• A multivariate model including mid-exercise VO2, CO, carbon dioxide production (VCO2), hemoglobin, and weight accurately predicted peak VO2 in HF patients.

Conclusions:

• Mid-exercise VO2 and CO are valuable predictors of peak exercise capacity in HF patients.
• These mid-exercise parameters can effectively identify patients with severe heart failure.
• Evaluating mid-exercise VO2 and CO offers significant clinical utility for HF patient management.