Real-time three-dimensional speckle tracking echocardiography: a novel technique to quantify global left ventricular mechanical dyssynchrony.
Résumé
AIMS: left ventricular (LV) mechanical dyssynchrony (LVMD) has emerged as a therapeutic target using cardiac resynchronization therapy (CRT) in chronic heart failure patients. Current methods used to evaluate LVMD are technically challenging and do not assess all the components of LVMD simultaneously. We analysed real-time 3D speckle tracking (3DST) echocardiography as a novel method to assess LVMD. METHODS AND RESULTS: three-dimensional ST was performed in 60 unselected patients (71 ± 9 years old; 39% with ischaemic cardiomyopathy) who were referred to optimize and to control of a CRT device; implanted according to current guidelines (9 added to be excluded from the protocol). Two standardized conditions [right ventricular (RV) versus an optimized biventricular (BiV) pacing modality] were tested. These two pacing modalities lead to two distinct electrical activation patterns. We sought to test the capability of 3DST to distinguish these two patterns. The LV ejection fraction was 24 ± 9 in the RV mode and 29 ± 10% in BiV. By 3DST, we measured global end-systolic LV deformation and dyssynchrony (standard deviation of the time to peak/16 LV-segment). The 3D radial strain increased from 13.8 ± 5.7 in the RV to 15.9 ± 6.5% in theBiV mode, and the dyssynchrony index decreased from 15.1 ± 5.0 to 11.8 ± 4.1%. 3D longitudinal strain increased from -6.9 ± 2.8 in the RV to -7.8 ± 3.2% in the BiV mode, and the dyssynchrony index decreased from 14.2 ± 4.8 to 11.5 ± 5.0% (P < 0.01 for all). The 3D area strain (AS) increased from -15.4 ± 6 in the RV to -18.3 ± 7.0% in the BiV mode, and the dyssynchrony index decreased from 12.2 ± 5.1 to 9.5 ± 4.5% (P < 0.001 for all). CONCLUSION: When image quality is optimal, 3DST might offer a new rapid method to quantify global LVMD in CRT candidates. In a comparison of the utility of various 3D strain measurements, the 3D AS appears to be closed to the ideal parameter that we are looking for.