Quantification of Left Ventricular Systolic Dyssynchrony by Real-Time Three-Dimensional Echocardiography

Objective To assess real-time 3-dimensional echocardiography (RT3DE)-derived left ventricular (LV) systolic dyssynchrony parameters: (1) normal values, (2) characteristics in patients with heart failure (HF) and a wide or narrow QRS complex, (3) interobserver and intraobserver variability with current state of the art RT3DE hardware and software technology, and (4) incremental value in patients with HF who receive cardiac resynchronization therapy (CRT). Methods The study involved 84 patients with HF (mean age 54 ± 15 years, 50 men) and 60 healthy volunteers (mean age 41 ± 15 years, 36 men). Semiautomated LV endocardial border tracking was used to calculate regional time-to-minimum systolic volume and to generate parametric maps and the systolic dyssynchrony index (SDI), defined as the standard deviation of time-to-minimum systolic volume of the 16 LV segments expressed in percentage of R-R duration. Results The volume rate of the RT3DE datasets in patients with HF was 31 ± 9 Hz (range 15-42 Hz). The normal value of the SDI was 4.1% ± 2.2% (range