Normalized left ventricular workload using phase-contrast magnetic resonance imaging in patients with aortic stenosis

Area of Science:

• Cardiovascular Imaging and Hemodynamics
• Biomedical Engineering
• Clinical Cardiology

Background:

• Aortic stenosis (AS) severity impacts left ventricle (LV) function by increasing hemodynamic load.
• Increased LV stroke work (SW) is a consequence of this altered load, representing the energy needed for blood ejection.
• Quantifying SW is essential for understanding AS progression and patient outcomes.

Purpose of the Study:

• To derive and evaluate left ventricle stroke work (SW) and normalized SW (N-SW) from cardiovascular magnetic resonance (CMR) data.
• To assess the utility of N-SW as a parameter for determining AS severity.
• To establish a potential threshold for N-SW in grading AS patients.

Main Methods:

• Utilized in-vivo cardiovascular magnetic resonance (CMR) velocity measurements from 57 patients.
• Employed a lumped-parametric model to derive stroke work (SW).
• Calculated normalized SW (N-SW) and correlated it with established AS severity markers like effective orifice area (EOA) and valvulo-arterial impedance (ZVA).

Main Results:

• Stroke work (SW) successfully differentiated between normal and low flow states (p<0.05).
• Normalized SW (N-SW) demonstrated significant associations with EOA (r=-0.5, p<0.001) and ZVA (r=0.65, p<0.001).
• A severity threshold for N-SW (1.5 cJ/mL) was identified using EOA=1 cm(2) as a marker.

Conclusions:

• CMR-derived SW and N-SW are potentially valuable tools for assessing AS severity.
• N-SW shows strong correlation with key hemodynamic parameters, supporting its use in AS grading.
• These non-invasive metrics may aid in the clinical management and stratification of patients with aortic stenosis.