Mechanical dyssynchrony assessed by tissue doppler imaging is a powerful predictor of mortality in congestive heart failure with normal QRS duration

OBJECTIVES: We sought to test whether the mechanical dyssynchrony assessed by tissue Doppler imaging (TDI) is a predictor of cardiac events in patients with congestive heart failure (CHF) and QRS duration ≤120 ms. BACKGROUND: The prevalence and prognostic value of mechanical dyssynchrony in patients with CHF and normal QRS duration have not been well clarified. METHODS: A total of 106 patients (age 63 ± 11 years) with CHF and ejection fraction (EF) <35% were followed serially; TDI was performed using four basal and four mid-left ventricular segments to assess the time to peak systolic point from R-wave on electrocardiogram (Ts). The standard deviation of Ts (Ts-SD) and the maximal temporal difference of Ts (Ts-diff) of eight segments were used as an indicator of mechanical dyssynchrony. Clinical events included readmission due to worsening of CHF, cardiac transplantation, and death. RESULTS: After 17 ± 11 months of follow-up, the clinical event rate was 33% including all-cause mortality of 19%. Prolonged Ts-SD (>37 ms) and Ts-diff (>91 ms) were associated with a significant increase in all clinical events. By multivariate analysis, Ts-diff (>91 ms) was an independent risk factor of clinical events and mortality regardless of age, EF, QRS duration, and use of beta-blocking agents. Mean event-free survival was 16.3 months (95% confidence interval [CI] 11.9 to 20.7) in patients with Ts-diff >91 ms and 31.6 months (95% CI 28.0 to 35.1) in those with Ts-diff ≤91 ms, respectively (p < 0.001). CONCLUSIONS: Myocardial dyssynchrony assessed by TDI is a powerful predictor of clinical events in CHF with normal QRS.