Objective: To examine the predictive value of systolic dyssynchrony measured by tissue Doppler velocity versus tissue Doppler strain imaging on long-term outcome after cardiac resynchronization therapy (CRT).
Design: Cohort study.
Setting: Two university hospitals.
Patients: Two hundred and thirty-nine patients (65±12 years, 76% males) who underwent CRT.
Interventions: Baseline echocardiography with tissue Doppler imaging (TDI) and clinical follow up for 37±20 months.
Main outcome measures: The time to peak systolic velocity during ejection phase (Ts) and the time to peak systolic strain (T∊) were assessed for dyssynchrony, i.e. the maximal delay in Ts and the maximal delay in T∊ among the 4 left ventricular basal segments. Occurrence of cardiovascular endpoints between patients with and without dyssynchrony was compared by Kaplan-Meier curves, followed by Cox regression analysis for potential predictor(s).
Results: There were 78 (33%) deaths, with cardiovascular causes in 64 (27%) patients, while 136 (57%) patients were hospitalized for cardiovascular events, including decompensated heart failure in 87 (36%) patients. Patients with the maximal delay in Ts ≥65ms showed a lower event rate for cardiovascular mortality (19% vs. 38%, Log-rank χ2=7.803, p=0.005) and other prognostic endpoints. In Cox regression analysis, the maximal delay in Ts (HR: 0.463, 95% CI: 0.270-0.792, p=0.005) and ischemic etiology (HR: 2.716, 95% CI: 1.505-4.901, p=0.001) were independent predictors of cardiovascular mortality. In contrast, the maximal delay in T∊≥80ms failed to predict any cardiovascular event.
Conclusions: Echocardiographic evidence of pre-pacing systolic dyssynchrony measured by TDI velocity, but not TDI strain, predicted lower long-term cardiovascular events after CRT.
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