Accuracy and reproducibility of biplane two-dimensional echocardiographic measurements of left ventricular dimensions and function

Abstract

ObjectivesTo investigate sources of variability in serial echocardiographic recordings in a core laboratory we assessed the impact of repeated echo recordings, repeated video measurements and measurements made by different investigators.Patients, methodsTwo investigators each recorded and analysed two-dimensional echos in 12 individuals (n=24 in total) three times at one week intervals. Left ventricular end-diastolic and end-systolic volumes were measured using the biplane modified Simpson's rule. Ejection fraction was derived from these volumes and left ventricular mass estimated using the area-length method. The left ventricular spherity index was expressed as the ratio of the short axis area and the long axis area at end-diastole. A video recording from each examination was reexamined twice by both investigators.ResultsDeviations between repeated echo recordings and repeated video measurements ranged from −5 to +5% between investigators. A three-way repeated analysis of variance indicated a small, but systematic difference between investigators. Reproducibility, measured by coefficients of variation, ranged from 3–9% for different investigators, 3–6% for repeated video measurements and 7–19% for repeated echo recordings across the different variables. The total variability of all three factors should be considered when the smallest detectable significant change in a variable is assessed. These ranged from 16–28% across the five variables studied, when a 10% error of classification was accepted for a one-sided change in a variable.ConclusionRepeated echo recordings were the dominant component of variation. Two-dimensional echo measurements are reproducible and accurate, but the same investigator should follow the same patients.