Interobserver reliability and accuracy of the visual assessment of interventricular septal flattening in pulmonary hypertension

Abstract

Background

Interventricular septal (IVS) flattening is a key echocardiographic feature of pulmonary hypertension (PH) that is associated with worse outcomes. The accuracy and interobserver reliability of visual and quantitative measures of IVS in PH patients are poorly described.

Methods

This single-center, retrospective analysis included 173 PH patients. All echocardiograms were independently interpreted by two board-certified echocardiographers, and IVS flattening was judged to be present visually and by calculating the eccentricity index (EI). A receiver operating characteristics analysis was conducted to determine the EI with the highest combination of sensitivity and specificity for visual IVS flattening. The agreement between the two echocardiographers for calculation of EI was assessed using Bland-Altman analysis.

Results

The overall percent agreement for visual IVS flattening was 72 % with a Kappa coefficient of 0.27. Agreement was highest for patients with pre-capillary PH and lowest for those with isolated post-capillary PH. An EI cut-off of 1.5 had the highest combination of specificity (80 %) and sensitivity (32 %) to distinguish visual septal flattening. Bland-Altman analysis showed wide 95 % limits of agreement between echocardiographers for EI measured during systole and diastole.

Interpretation

There was a fair degree of agreement between two echo readers for the presence or absence of IVS flattening, which differed based on the hemodynamic subgroup of PH. Compared to the quantitative measure EI, visual assessment had a moderately high specificity but very low sensitivity for the presence of IVS flattening. Automated measures of IVS flattening should be considered to improve the accuracy and reliability of this key metric.