Shear wave elastography using high frame rate imaging in the follow-up of heart transplant recipients

ABSTRACT Background After orthotopic heart transplantation (HTx), allografts undergo diffuse myocardial injury (DMI) that contributes to functional impairment, especially to increased passive myocardial stiffness, which is an important pathophysiological determinant of left ventricular (LV) diastolic dysfunction. Echocardiographic shear wave (SW) elastography is an emerging approach for measuring myocardial stiffness in vivo. Natural SWs occur after mechanical excitation of the myocardium, e.g. after mitral valve closure (MVC) and their propagation velocity is directly related to myocardial stiffness, thus providing an opportunity to assess myocardial stiffness at end-diastole. Objectives To investigate if propagation velocities of naturally occurring SWs at MVC increase with the degree of DMI and with invasively determined LV filling pressures as a reflection of an increase in myocardial stiffness in HTx recipients. Methods 52 HTx recipients that underwent right heart catheterization (all) and cardiac magnetic resonance (CMR, n=23) during their annual check-up were prospectively enrolled. Echocardiographic SW elastography was performed in parasternal long axis views of the LV using an experimental scanner at 1135 ± 270 frames per second. The degree of DMI was quantified with T1 mapping. Results SW velocity at MVC correlated best with native myocardial T1 values (r=0.80, p Conclusions End-diastolic shear wave propagation velocities, as measure of myocardial stiffness, showed a good correlation with CMR defined diffuse myocardial injury and with invasively determined left ventricular filling pressures in HTx patients. These findings thus suggest that shear wave elastography has the potential to become a valuable non-invasive method for the assessment of diastolic myocardial properties in heart transplant recipients.