Interobserver Variability of Left Ventricular Measurements in a Population of Predominantly Obese Hypertensives Using Simultaneously Acquired and Displayed M‐Mode and 2‐D Cine Echocardiography

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Abstract
Achieving low interobserver variability is a goal of echocardiographic determined left ventricular (LV) mass measurements. In a group of hypertensives, we evaluated interobserver variation using a method of simultaneously acquired two-dimensional (2-D) cine and M-mode images displayed in a split screen format. Sixty echocardiographic images from ongoing hypertension trials, including serial studies of the same patients, were obtained with an UltraMarktrade mark 6 Ultrasound System (Advanced Technology Laboratories, Inc., Bothell, WA, USA). Images were digitized online, coded with a random number, and pooled prior to the analysis to minimize observer bias. Studies were read by two independent observers in a blinded fashion and in a random order using a Color Vue II Nova MicroSonicstrade mark analyzer (Nova Microsonics, Mahwah, NJ, USA). The M-mode tracing and cine of three consecutive frames of 2-D parasternal short-axis views of the LV were simultaneously displayed in a split screen format. The 2-D cine was used as a reference image during M-mode measurements of LV dimensions. Measurements were obtained and the LV mass estimated according to the Penn convention. Interobserver variability for left ventricular internal dimension (LVID), interventricular septal thickness (IVS), posterior wall thickness (PWT), and left ventricular mass (LV mass) is low when either correlated (Pearson correlation coefficients of 0.94, 0.82, 0.75, and 0.93, respectively) or expressed as a percent of the mean (3.0%, 10.0%, 10.2%, and 8.9%, respectively). When read in a blinded fashion, interobserver variability (especially for LV mass) is small using digitized, simultaneously acquired and displayed cines of 2-D and M-mode echocardiograms. This is likely due to the ability to discriminate myocardial wall edges (endocardium) from other associated structures such as tricuspid and mitral apparatus. This method may prove useful in studies of LV mass.