Current Role of Echocardiography in Cardiac Resynchronization Therapy: from Cardiac Mechanics to Flow Dynamics Analysis.

CRT is an established treatment for patients with heart failure and left ventricular systolic dysfunction. In the current guidelines, CRT implant indications rely only on electrical dyssynchrony, but in the last years, many aspects of cardiac mechanics (including contractile synchrony, coordination, propagation, and myocardial work) and flow dynamics have been studied using echocardiographic techniques to better characterize patients undergoing or with implanted CRT. However, the concepts, limits, and potential applications of all these echocardiographic evaluations are unclear to most clinicians. The use of left ventricular dyssynchrony and discoordination indices may help to identify those significant mechanical alterations whose correction may increase the probability of a favorable CRT response. Assessment of myocardial work and intracardiac flow dynamics may overcome some limitations of the conventional evaluation of cardiac mechanics but more investigations are needed before extensive clinical application.