Analysis of temporal delay in myocardial deformation throughout the cardiac cycle: Utility for selecting candidates for cardiac resynchronization therapy

BACKGROUND Analysis of myocardial strain using two-dimensional (2D) echocardiography to assess left ventricular (LV) mechanical dyssynchrony by measuring time differences in peak systolic strains from opposing LV walls has been proposed. However, peak systolic strain may be difficult to identify. OBJECTIVE The purpose of this study was to evaluate (1) LV dyssynchrony by assessing the overlap among strain traces of the LV walls throughout the cardiac cycle and (2) its usefulness in identifying responders to cardiac resynchronization therapy (CRT). METHODS Fifty patients with heart failure and LV systolic dysfunction undergoing CRT were studied with 2D echocardiography at baseline and 6-month follow-up. Myocardial radial strain and circumferential strain were analyzed using commercially available software. The resulting strain traces were postprocessed with a mathematical script. RESULTS Quantification of LV dyssynchrony was expressed as an index of temporal overlap from the analyzed traces. Responders to CRT were defined by >= 15% reduction of LV end-systolic volume at 6-month follow-up. Responders to CRT had higher LV dyssynchrony in both radial strain and circumferential strain analysis. A cutoff time overlap >= 7% for radial strain (area under the curve 0.79) and >= 8.5% for circumferential strain (area under the curve 0.66) identified responders to CRT. CONCLUSION Quantifying the temporal superposition of LV wall deformations with a computed algorithm allows measurement of LV intraventricular dyssynchrony throughout the cardiac cycle. The derived index is useful in stratifying the probability of response to CRT.