The split that is given corresponds to the one used in our paper:

S. Leclerc, E. Smistad, J. Pedrosa, A. Ostvik, et al.
"Deep Learning for Segmentation using an Open Large-Scale Dataset in 2D Echocardiography" in IEEE Transactions on Medical Imaging, vol. 38, no. 9, pp. 2198-2210, Sept. 2019
doi: 10.1109/TMI.2019.2900516

However, please note that a few corrections have been made, resulting in slight changes in distribution compared with the figures given in the article.