Comparison between Tissue Doppler Imaging (TDI) and Tissue Synchronization Imaging (TSI) in Evaluation of Left Ventricular Dyssynchrony in Patients with Advanced Heart Failure

Background: Assessment of left ventricular (LV) dyssynchrony has an important role in optimizing the selection of cardiac resynchronization therapy (CRT) candidates. We compared a new semiautomatic echocardiographic modality, tissue synchronization imaging (TSI) with a manual method, color-coded tissue Doppler imaging (TDI), in the assessment of LV dyssynchrony in patients with heart failure (HF). Methods: Ninety-five patients (age = 54.5 ± 17.1 years, 66.3% male) with advanced HF (NYHA functional class ≥III and ejection-fraction ≤35%) were included in the study and evaluated echocardiographically. The time to regional peak systolic velocity (Ts) in six basal and six middle segments of the LV was measured manually using velocity curves from TDI and semiautomatically using TSI and seven parameters of systolic dyssynchrony were computed. Results: Overall, a moderate-to-good association was found between Ts derived by these two modalities, whereas the mean of Ts via TSI was significantly lower than that measured by TDI in many LV segments. The agreement between these two modalities in identifying LV dyssynchrony varied from weak to moderate according to various dyssynchrony indices. In comparison to the TDI-derived dyssynchrony indices, TSI showed a high sensitivity of more than 90% using Ts delay at the basal/all LV segments and the indices for their standard deviations (SD) for identifying LV dyssynchrony, whereas the highest specificity of 80% was achieved using the septal-lateral dyssynchrony index in the prediction of LV dyssynchrony. Conclusion: With the aid of selected LV dyssynchrony indices, the TSI method may confer enough sensitivity for a speedy evaluation and initial screening of LV dyssynchrony in HF patients; however, the current technology of TSI does not seem specific enough to replace TDI in the evaluation of dyssynchrony. (Echocardiography 2012;29:7-12)