Abstract 2818: Larger Regions of Interest Reduce the Variability in Tissue Doppler Echocardiographic Measures of Dyssynchrony
Tissue Doppler echocardiographic dyssynchrony parameters failed to predict response to cardiac resynchronization therapy (CRT) in the multicenter Predictors of Response to CRT (PROSPECT) trial. This failure was thought to be due in part to the large variability arising from technical factors. For example, shifting the tissue Doppler region of interest (ROI) slightly within the myocardial wall can substantially alter the shape of the velocity curve generated from that ROI. These subtle changes in the velocity curves can lead to large variability when calculating dyssynchrony parameters. We hypothesized that using larger ROIs would significantly reduce the variability arising from manual placement of the ROIs. Variability of dyssynchrony parameters was determined for three ROI sizes (6x6, 18x6, 30x6 mm) in 30 patients undergoing CRT. Variability for each ROI size was simulated by placing 3 ROIs in each myocardial segment (Fig 1A–B⇓). Thus, 3 velocity curves were generated for each segment and each ROI size. Six published dyssynchrony parameters were calculated multiple times for each patient using all permutations of the 3 ROI positions. A mean modified coefficient of variation was calculated for each ROI size. The 6x6mm ROI had a mean coefficient of variation of 25% across all patients and parameters. The larger ROIs had significantly lower (both p<0.001) coefficients of variation compared to the 6x6mm ROI (Fig 1C⇓). Using a larger region of interest to quantify tissue Doppler dyssynchrony reduces variability by 44%. Regions of interest of 18x6 to 30x6mm should be used in future trials to minimize variability in a broad clinical setting.
This research has received full or partial funding support from the American Heart Association, AHA Greater Southeast Affiliate (Alabama, Florida, Georgia, Louisiana, Mississippi, Puerto Rico & Tennessee).