Vector Flow Mapping (VFM) is a novel technique for visualizing intracardiac blood flow. A few reports have been made regarding the reproducibility of energy loss (EL) measurements using VFM. This study aims to elucidate the intra-class and inter-class correlation coefficient (intra-ICC and inter-ICC) in the EL measurements.

Seven healthy participants were enrolled, and echocardiographic data were obtained by two cardiac sonographers (14 images). Three independent analysts analyzed all images in three different cardiac cycles three times: 378 data points (14 images × analysts × 3 cardiac cycles × 3 times). The intra-ICC (1, 1) and inter-ICC (2, 1) were calculated. Furthermore, the intra-ICC (1, k) and inter-ICC (2, k) were applied using the averaged EL value in three cardiac cycles. An ICC value greater than 0.75 was defined as acceptable reproducibility.

In diastole, the intra-ICC (1, 1) by the three analysts was 0.890, 0.830, and 0.802; the intra-ICC (1, k), using the average EL value was 0.986, 0.978, and 0.973. In systole, the intra-ICC (1, 1) was 0.729, 0.698, and 0.733; the intra-ICC (1, k) was 0.960, 0.954, and 0.961. In diastole, the inter-ICC (2, 1) was 0.950, and the inter-ICC (2, k) was 0.958. In contrast, in systole, the inter-ICC (2, 1) was 0.772, and the inter-ICC (2, k) was 0.774; these values were lower than those in diastole.

These findings indicate that the intra- and inter-measurer reproducibility of diastolic and systolic EL is favorable for clinical use.