ACCURACY AND REPRODUCIBILITY OF BIPLANE 2-DIMENSIONAL ECHOCARDIOGRAPHIC MEASUREMENTS OF LEFT-VENTRICULAR DIMENSIONS AND FUNCTION

Objective To investigate sources of variability in serial echocardiogr aphic recordings in a core laboratory we assessed the impact of repeat ed echo recordings, repealed video measurements and measurements made by different investigators. Patients, methods Two investigators each r ecorded and analysed two-dimensional echos in 12 individuals (n=24 in total) three times at one week intervals. Left ventricular end-diastol ic and end-systolic volumes were measured using the biplane modified S impson's rule. Ejection fraction was derived from these volumes and le ft ventricular mass estimated using the area-length method. The left v entricular spherity index was expressed as the ratio of the short axis area and the long axis area at end-diastole. A video recording from e ach examination was reexamined twice by both investigators. Results De viations between repeated echo recordings and repealed video measureme nts ranged from -5 to +5% between investigators. A three-way repeated analysis of variance indicated a small, but systematic difference betw een investigators. Reproducibility, measured by coefficients of variat ion, ranged from 3-9% for different investigators, 3-6% for repeated v ideo measurements and 7-19% for repeated echo recordings across the di fferent variables. The total variability of all three factors should b e considered when the smallest detectable significant change in a vari able is assessed. These ranged from 16-28% across the five variables s tudied, when a 10% error of classification was accepted for a one-side d change in a variable. Conclusion Repeated echo recordings were the d ominant component of variation. Two-dimensional echo measurements are reproducible and accurate, but the same investigator should follow the same patients.