Contrast Echocardiography Improves Interobserver Agreement for Wall Motion Score Index and Correlation with Ejection Fraction

Abstract

The wall motion score index (WMSI) is a surrogate for left ventricular ejection fraction (LV-EF), which becomes unreliable in poor echo windows. The value of contrast LV opacification (LVO) for WMSI assessment is not well known. We sought to compare interobserver agreement for WMSI and the correlation between the LVO-WMSI and LV-EF using two-dimensional second harmonic (SH) and LVO echocardiography. The study comprised 100 consecutive patients (57 ± 13 years, 85% males). Two independent physicians assessed LV segmental quality and wall motion for both the SH and LVO studies according to a 17-segment model. Systolic wall motion was defined as: normokinesia, hypokinesia (systolic inward endocardial motion <7 mm), akinesia, and dyskinesia. LV-EF was assessed from the LVO images according to the biplane modified Simpson's method. Of the 1,700 analyzed segments, 453 (26.6%) were poorly visualized with SH imaging, and 173 (10.2%) with LVO (P < 0.0001). The two observers agreed on segmental wall motion score in 1,299 segments (agreement 76%, Kappa 0.60) with SH imaging and in 1,491 segments (agreement 88%, Kappa 0.78) with LVO. Interobserver correlation (r(2) ) was 0.86 for the SH-WMSI and 0.93 for the LVO-WMSI. The limits-of-agreement for interobserver LVO-WMSI (mean difference -1.0%± 6.8%, agreement -14.6%, 12.6%) was lower than that for SH-WMSI (mean difference -2.3%± 10.1%, agreement -22.5, 17.9). The LVO-WMSI correlated well with LV-EF (r(2) = 0.71). LV-EF could be estimated according to the formula 1.01 - 0.32 × WMSI. Echo-contrast improves interobserver agreement for wall motion scoring and the WMSI. The LVO-imaged WMSI correlates well with LV-EF.