Can non-invasive myocardial stiffness measurements characterize the dysfunctional septum in the presence of a left bundle branch block?

Heart failure is a progressive disease with a morbidity and mortality similar to cancer. It is often associated with a left bundle branch block(LBBB) conduction delay, causing typical left ventricular (LV) remodelling with a thin and dysfunctional septal wall. Cardiacresynchronization therapy (CRT) can compensate for the conduction delay and may reverse the remodelling, mainly by recovering septal function. Unfortunately, its non-responder rate is 40%. We recently showed that septal scar has significant impact on the response to CRT. However, around 40% of CRT candidates cannot undergo an MRI, the gold standard to assess scar. Other imaging modalities are unreliable, as the thin and dysfunctional septum makes it difficult to differentiate scar from viable myocardium. Shear wave imaging is a novel method to non-invasively assessmyocardial stiffness. Being based on echocardiography, it can be applied to all patients. We have shown that stiffness measurements can distinguish scarred from normal myocardium. We therefore hypothesize that it can differentiate a non-viable scarred septum from a remodelled but viable septum also in the presence of LBBB. We will test this hypothesis in animal experiments and patients. The project will provide (1) new insights into the interaction of scar and LBBB on LV function, and (2) a new way to characterize the remodelled septum, and potentially a clinically useful criterion for better selection of all CRT candidates.