Abstract
[Background] An impairment of the global left ventricular (LV) relaxation is potential to identify patients at a risk of increased incidence of morbidity and mortality in patients with congestive heart failure (CHF). Previous reports have demonstrated that tissue Doppler and speckle tracking imaging methods serve as a quantitative assessment of LV relaxation using strain rate (SR) during isovolumic relaxation time (IVR). [Aim] This study was aimed to characterize the ability of global SR during IVR (SR-IVR) using speckle tracking imaging in predicting the outcome in patients with non-ischemic dilated cardiomyopathy (DCM). [Method] This study included 52 consecutive patients with DCM (38 male, 57+/−14 years) without overt CHF at the enrollment. We excluded patients with atrial fibrillation, complete left bundle branch block and predominant valvular heart diseases. The color-coded tissue Doppler and two-dimensional images were obtained with GE Vivid 7 in the 3 apical views for analyzing the global indexes of LV dyssynchrony (Ts-SD: standard deviation of time to peak systolic velocity in 12 LV model) and relaxation (SR-IVR: averaged longitudinal SR during IVR in 18 LV model). In addition, the levels of B-type natriuretic peptide (BNP) were also measured. Cardiac events were defined as the composite incidence of sudden cardiac death, hospitalization for worsening heart failure, and refractory CHF such as NYHA class III or IV despite of optimal medical therapy during the follow-up period. [Results] The mean values of LV ejection fraction (EF), Ts-SD, SR-IVR and BNP were 37.8%, 36.3 ms, 0.15/s and 274 pg/ml, respectively. SR-IVR was closely associated with LV end-systolic volume index (ESVI), Ts-SD and BNP (p<0.01 for all). During the follow-up period (mean, 22+/−14 months), 15 patients had cardiac events and the negative value of SR-IVR was observed in 8 out of 15 patients with cardiac events. Multivariate analysis showed that among age, EF, ESVI, Ts-SD and SR-IVR, SR-IVR was the only independent echocardiographic predictor of cardiac events in this study population (β= 0.486, p< 0.01). [Conclusion] The reduction and negative value of global SR-IVR was shown to be a robust echocardiographic parameter for poorer outcomes in patients with DCM.
Published Version
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