Shear Wave Elastography Using High-Frame-Rate Imaging in the Follow-Up of Heart Transplantation Recipients

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Imaging

Background:

• Heart transplantation (HTx) recipients often develop diffuse myocardial injury (DMI), leading to increased myocardial stiffness and diastolic dysfunction.
• Echocardiographic shear wave (SW) elastography is an emerging technique to measure myocardial stiffness in vivo.
• Naturally occurring SWs after mitral valve closure (MVC) provide a direct measure of myocardial stiffness at end-diastole.

Purpose of the Study:

• To investigate if SW propagation velocities at MVC increase with diffuse myocardial injury (DMI) and invasively determined left ventricular (LV) filling pressures.
• To assess the correlation between SW velocity and myocardial stiffness in HTx recipients.

Main Methods:

• Prospective enrollment of 52 HTx recipients undergoing right heart catheterization and 23 undergoing cardiac magnetic resonance (CMR).
• Echocardiographic SW elastography performed in parasternal long axis views of the LV.
• Quantification of DMI using T1 mapping on CMR.

Main Results:

• SW velocity at MVC showed the strongest correlation with native myocardial T1 values (r=0.75; p<0.0001).
• SW velocity was the best noninvasive parameter correlating with pulmonary capillary wedge pressures (PCWP) (r=0.54; p<0.001).
• Standard echocardiographic LV diastolic function parameters showed poor correlation with native T1 and PCWP.

Conclusions:

• End-diastolic SW propagation velocities correlate well with CMR-defined DMI and invasively determined LV filling pressures in HTx patients.
• SW elastography shows potential as a valuable noninvasive tool for assessing diastolic myocardial properties in HTx recipients.