"Regarding the low LDL group results, we need to know if most of the low GFR patients happened to be in that group. I’m trying to find that out."

According to baseline LDL-C for total and CKD population shown in the poster below, both the total population and CKD population had the same median and interquartile range. So it seems that answer to your question is no. One cannot explain the below median LDL-C MACE reduction by it being due to low eGFR. The eGFR and LDL-C MACE reduction observations appear to be independent of one another.

https://www.resverlogix.com/upload/media_element/177/76b2a9c98699/2019-09-02-esc-design-poster-final.pdf