Test-retest variability for quantitative two-dimensional and Doppler measurements in the fetus

Observed and expected reliability of echocardiographic volumetric methods and critical change values for quantification of mitral regurgitant fraction in dogs

BACKGROUND

Reliability of echocardiographic calculations for stroke volume and mitral regurgitant fraction (RFMR) are affected by observer variability and lack of a gold standard. Variability is used to calculate critical change values (CCVs) that are thresholds representing real change in a measure not associated with observer variability.

HYPOTHESIS

Observed intra- and interobserver accuracy and variability in healthy dogs help model CCV for RFMR.

ANIMALS

Reliability cohort of 34 healthy dogs; allometric scaling cohort of 99 dogs with heart disease and 25 healthy dogs.

METHODS

Accuracy, variability, and CCV of 2 observers using geometric and flow-based echocardiography were prospectively compared against a standard of RFMR = 0% and extrapolated across a range of expected RFMR values in the reliability cohort partly derived from cardiac dimensions predicted by the allometric cohort.

RESULTS

Accuracy of methods to determine RFMR in descending order was 4-chamber bullet (Bullet4CH), mitral inflow, cube formula, and Simpson's method of disks. Intraobserver variability was relatively high. The CCV for RFMR ranged from 28% to 88% and was inversely related to RFMR when extrapolated for use in affected dogs. For both observers, the Bullet4CH method had the lowest intraobserver CCV (Operator 1:28%, Operator 2:41%). Interobserver strength of agreement was low with intraclass correlation coefficients ranging from 0.210 to 0.413.

CONCLUSIONS AND CLINICAL IMPORTANCE

Echocardiographic volumetric methods used to calculate stroke volume and RFMR have low accuracy and high variability in healthy dogs. Extrapolation of observed CCV to a range of expected RFMR suggests observers and methods are not interchangeable and variability might hinder routine clinical usage. Individual observers should be aware of their own variability and CCV.

Reference ranges for the fetal mitral, tricuspid, and interventricular septum annular plane systolic excursions (mitral annular plane systolic excursion, tricuspid annular plane systolic excursion, and septum annular plane systolic excursion) between 20 and 36 + 6 weeks of gestation

Objectives This study aimed to establish reference ranges for fetal mitral, tricuspid, and interventricular septum annular plane systolic excursions (MAPSE, TAPSE, and SAPSE) in normal pregnant women between 20 and 36 + 6 weeks of gestation. Methods This prospective and cross-sectional study included 360 low-risk singleton pregnancies between 20 and 36 + 6 weeks of gestation. MAPSE, TAPSE, and SAPSE were measured by M-mode in real time in an apical or basal four-chamber view through placing the cursor at the atrioventricular junction, marked by the valve rings at the tricuspid, mitral, and basal septum, respectively. A regression analysis was done to determine the appropriate polynomial equation model for both measurements and standard deviation (SD) values in relation to gestational age (GA). The intra- and inter-observer reproducibility was evaluated using the concordance correlation coefficient (CCC) and limits of agreement (LoA). Results There was a significant positive correlation between MAPSE (r=0.705, p<0.0001), TAPSE (r=0.804, p<0.0001), and SAPSE (r=0.690, p<0.0001) and GA. The mean of each parameter ranged as follows: 2.87-5.56 mm, MAPSE; 3.98-8.07 mm, TAPSE; and 2.34-4.21 mm, SAPSE. Poor/moderate intra- and inter-observer reliability (CCC between 0.70 and 0.90) and poor/moderate agreement of all the tested parameters were evaluated (LoA between 10 and 50%). Conclusions Reference values were established for the fetal MAPSE, TAPSE, and SAPSE between 20 and 36 + 6 weeks of gestation in low-risk pregnant women. These parameters showed poor/moderate reproducibility.

Reference ranges for the left ventricle modified myocardial performance index, respective time periods, and atrioventricular peak velocities between 20 and 36 + 6 weeks of gestation

Objective: To establish reference ranges for the fetal left ventricle (LV) modified myocardial performance index (Mod-MPI), respective time periods, and right and left atrioventricular peak velocities between 20 and 36 + 6 weeks of gestation.Methods: This cross-sectional study evaluated 360 low-risk singleton pregnancies between 20 and 36 + 6 weeks of gestation. The LV Mod-MPI was calculated as (isovolumetric contraction time + isovolumetric relaxation time)/ejection time. Polynomial regression was used to obtain the best-fit using Mod-MPI and atrioventricular peak velocity measurements and gestational age (GA) with adjustments using the coefficient of determination (R²). The intra- and interobserver reliability was evaluated using the concordance correlation coefficient (CCC).Results: LV Mod-MPI (R² = 0.026, p = .002) and isovolumetric relaxation time (IRT) (R² = 0.036, p < .001) significantly increased with advancing GA. Isovolumetric contraction time (ICT) and ejection time (ET) did not significantly change with GA. RV and LV E wave, A wave, and E/A ratio significantly increased with GA (p < .001). The mean of each parameter ranged as follows: LV Mod-MPI (0.44-0.47 s), IRT (0.041-0.045 s), ICT (0.032-0.034 s), ET (0.167-0.167 s), RV E (30.2-46.91 cm/s), RV A (47.1-60.7 cm/s), RV E/A (0.65-0.78 cm/s), LV E (27.0-41.4 cm/s), LV A (43.2-53.8 cm/s), and LV E/A (0.63-0.78 cm/s). Only LV A wave measurements demonstrated an intraobserver CCC >0.80. The remaining intra- and interobserver reproducibility parameters demonstrated lower CCC.Conclusions: Reference values were replicated for the fetal LV Mod-MPI and LV and RV transvalvular peak velocities between 20 and 36 + 6 weeks of gestation.