Validation of shear wave elastography for assessing myocardial fibrosis in patients with end-stage heart failure

Myocardial fibrosis plays a crucial role in the pathophysiology of heart failure, increases myocardial stiffness, impairs diastolic function and is associated with adverse outcomes. Shear wave elastography (SWE) uses high frame rate echocardiography to assess shear waves in the myocardium. This technique may permit assessment of myocardial stiffness by measuring the propagation speed of myocardial shear waves. We aimed to validate the ability of SWE to assess the degree of myocardial fibrosis in patients with end-stage heart failure.

We performed high frame rate echocardiography in 16 heart failure patients who were listed for heart transplantation and 16 age- and sex-matched healthy control subjects. Naturally occurring shear waves triggered by mitral valve closure (MVC) and aortic valve closure (AVC) were analyzed by tissue Doppler imaging in the interventricular septum. Septal shear wave velocities were compared with septal collagen volume fraction (CVF) in explanted hearts. Mean septal CVF in cardiac explants was 17.1 ± 7.6%. AVC and MVC wave velocities were associated with septal CVF (Spearman's correlation of mean septal values: ρ = 0.75, P = 0.02 and ρ = 0.65, P = 0.03, respectively). Similar results were observed in linear mixed-effects regression analysis by septal region (AVC wave: β = 2.2, 95% CI [0.7, 3.8], P = 0.004; MVC wave: β = 1.5, 95% CI [0.4, 2.5], P = 0.005). Shear waves could be measured in most patients but were limited by patient factors such as prosthetic valves and left ventricular assist devices.

Shear wave velocities from SWE correlate with CVF. SWE therefore hold promise as a novel non-invasive method for assessing myocardial fibrosis.