Real time three-dimensional transthoracic echocardiographic segmental volume analysis: quantitative and objective tool for assessing regional wall motion abnormalities in ischemic heart disease

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Evaluation of regional wall motion abnormality (RWMA) by 2D echocardiography (2DE) plays an important role in the diagnosing ischemic heart disease (IHD). However, 2DE is disadvantaged by being subjective, semi-quantitative, and expert-dependent. Recently, a method of measuring LV segmental volume by 3DE has been introduced, which enabled volume changes in LV regional to be measured. This study aimed to demonstrate the clinical usefulness of 3DE segmental volume analysis as an objective and quantitative tool for assessing RWMA in patients with IHD. Methods 33 patients with ischemic heart disease confirmed by coronary aniography and showing single vessel territory RWMA by 2DE were retrospectively enrolled. In the 2DE study, RWMAs were evaluated visually by and experienced physicians, and 17-segment bull's-eye polar maps were generated using a two-point scale, viz. 'normal' (showing normal contractility) or 'abnormal' (showing hypokinesis or akinesis). Culprit vessel territories were specified by a physician based on typical coronary artery distributions. In the 3DE study, two independent observers analyzed data using QLAB 3D quantification advanced software (version 10.0, Philips Healthcare). Segmental volumes of 17 LV segments were measured using a predetermined algorithm, and segmental volume ejection fractions (SVEFs) were calculated. Receiver operating characteristic (ROC) curve analysis was used to determine the SVEF cut-off value that best differentiated 'normal' and 'abnormal'. Using this cut-off value, 17-segment bull's-eye polar maps were generated. Reliability of correct predicting the culprit coronary arteries by 3DE bull's-eyes compared to 2DE ones was evaluated using Cohen's kappa co-efficients, which were also used for inter- and intra-observer variability analysis of 3DE bull's-eye derived culprit coronary artery predictions. Results Mean 3DE SVEFs were significantly lower for segments showing RWMA by 2DE. Additionally, among the segments determined to be normal by 2DE, 3D basal segmental EF is statistically lower than mid- and apical ones. The optimum SVEF cut-off value was 44%, with a sensitivity of 75.0% and a specificity of 73.9% (AUC = 0.801, 95% CI 0.763–0.838, p<0.001). The reliability of 3DE bull's-eye derived culprit coronary artery predictions was 81.8% (kappa = 0.672, 95% CI 0.555–0.789, p<0.001). Inter- and intra-observer variabilities of 3DE bull's-eye derived culprit coronary artery predictions were 97.0% (kappa = 0.947, 95% CI 0.894–0.100, p<0.001) and 93.9% (kappa = 0.897, 95% CI 0.827–0.967, p<0.001), respectively. Conclusion Assessment of RWMA using 3D echocardiographic segmental volume analysis was found to be feasible and reproducible, and its predictions of culprit coronary arteries well matched those of 2DE. 3DE segmental volume analysis could be used as a quantitative and objective tool for assessing RWMA in ischemic heart disease patients.