Left ventricular volume regulation in heart failure with preserved ejection fraction

Area of Science:

• Cardiology
• Physiology
• Biomedical Engineering

Background:

• Ejection Fraction (EF) is widely used but faces criticism for universal applicability.
• The emergence of heart failure with preserved ejection fraction (HFpEF) highlights EF's limitations.
• Traditional methods like the Starling curve have limitations in fully explaining ventricular function.

Purpose of the Study:

• To critically examine the limitations of Ejection Fraction (EF) in assessing global ventricular performance.
• To introduce and validate a novel cardiac input-output volume regulation framework.
• To differentiate patterns of ventricular function in heart failure with preserved ejection fraction (HFpEF) versus reduced ejection fraction (HFrEF).

Main Methods:

• Analysis of the relationship between end-systolic volume (ESV) and end-diastolic volume (EDV).
• Comparison of ESV-EDV regression slopes between HFpEF patients (n=34) and controls with EF < 50% (n=29).
• Validation of findings using data from two independent publications.

Main Results:

• A distinct ESV-EDV pattern was identified in patients with HFpEF.
• A statistically significant difference (P < 0.0004) in the ESV-EDV regression slope was observed between HFpEF and HFrEF groups.
• The volume regulation approach using primary determinants (ESV, EDV) proved advantageous over derived metrics like EF.

Conclusions:

• The ESV-EDV volume regulation model offers a more fundamental characterization of ventricular function.
• This approach clarifies the distinct pathophysiological mechanisms underlying HFpEF and HFrEF.
• The proposed framework provides a basis for understanding why patients present with either preserved or reduced EF in heart failure.