Abstract 1577: Variability of Serial Left Atrial Volume Index Measurements by 2-D Echo in a Randomized Clinical Trial: An Echo Core Lab Study
Introduction: Left atrial volume index (LAVI) is associated with adverse cardiac events and is a measure of chronicity of LV diastolic dysfunction. LAVI has been proposed as a primary outcome measure in clinical trials. In a randomized clinical trial, the Echo Core lab performed standard 2-D echo measurements and sought to examine the variability of LAVI over time.
Methods One hundred twenty men (mean age 42 ± 9 years), free of cardiac disease, underwent 2 serial echos (baseline, 12 weeks) to test safety of 3 topical solution treatments for androgenic alopecia including an investigational treatment. LA volumes were measured by 3 senior sonographers using biplane Simpson’s (S) and area-length (AL) methods and indexed to body surface area. A Pearson correlation coefficient was calculated for all individuals to measure strength of relation of LA volumes between the 2 methods, but also using the same method over time. The Bland-Altman method was used to evaluate the limits of agreement of the methods (not shown). Inter- and Intra-observer variability was calculated using 14 subjects and expressed as mean ± SD.
Results: Baseline overall mean LAVI was 21.2 ± 5.2 ml/m2 by (S). LAVI calculated by the +2 methods compared closely (r = 0.93, mean difference 1.4 ± 2.0) and demonstrated low inter- and intra-observer variability. However, serial measurements in the same individual 12 weeks apart showed significant variability and fair correlation (r=0.61) in LAVI using either method. Mean differences over time were small but the SD was 4.9 and 4.8 ml/m2 for the (AL) and (S) methods, respectively.
Conclusions: In a randomized clinical trial, LAVI measurements by the Echo Core lab showed high correlation between Simpson’s and Biplane area-length methods and low inter- and intra-observer variability. However, serial LAVI measurements over time in the same healthy individuals showed wide variability, limiting the potential utility of LAVI by 2-D Echo as a primary outcome measure.