11-14) Of note, TDI velocity is almost the exclusive modality adopted for measurement, because of the discernable and consistent signal of early diastole (Table 1). Dyssynchrony and CRT The compelling evidence from multicenter clinical trials has established CRT as the most promising therapeutic modality in heart failure management over the past decade.15) Inhibitors,research,lifescience,medical CRT not only improves symptoms and cardiac function, but also reduces heart failure hospitalization and all-cause/cardiovascular mortality in patients with advanced CHF. However, it remains a major problem that non-responders of therapy are constantly observed in about one-third

of patients receiving CRT, based on the current guidelines for patient selection in which the QRS duration ≥ 120 ms is regarded as the only marker of ventricular electromechanical Inhibitors,research,lifescience,medical delay.16),17) The presence of a prolonged QRS duration

in CHF is associated with more advanced myocardial disease, more severe LV dysfunction, worse prognosis and higher selleck chemicals llc all-cause mortality.18) However, a prolonged QRS duration may not necessarily be equivalent to significant mechanical dyssynchrony, even in the form of left bundle branch block (LBBB). Inhibitors,research,lifescience,medical Fung et al.19) observed that regional electrical conduction delay could be absent in CHF patients with LBBB. Using the 3D non-contact mapping electrograms, homogenous delay in LV the propagation

of endocardial activation similar to that of normal subjects was found in some patients with typical LBBB, while typical delay Inhibitors,research,lifescience,medical in depolarization over the LV lateral or posterior wall was observed in others. In fact, the QRS duration on surface ECG is a rather inaccurate estimation of myocardial electrical activation which correlates poorly with the occurrence of systolic mechanical dyssynchrony.20-22) The correction of cardiac electromechanical delay is suggested to be one of Inhibitors,research,lifescience,medical the major mechanisms for CRT benefits. Therefore, direct measurement of mechanical dyssynchrony by echocardiography has become clinically relevant in estimating the likelihood of response when ECG as a surrogate marker may fail. Over the last decade, a number of single-center studies have demonstrated that the lack of mechanical dyssynchrony PDK4 assessed by noninvasive echocardiographic techniques is closely related to the lack of response in patients who received CRT. Nevertheless, those results were challenged by the Predictors of Response to CRT (PROSPECT) trial, the first multicenter trial in which no single echocardiographic measure of mechanical dyssynchrony could predict CRT responses with a good sensitivity and specificity.