To put this really simply, it means there is heart disease at work. Reversible means the blockages are not total, and no heart muscle is damaged, so intervention with stents or bypass will make things much improved. If the blockages are not severe enough, they may try to help with medication. I think you will be required for an Angiogram next to see the exact extent of the disease.
Oh just to add, your Ejection Fraction is fine. When your heart beats, it pushes out some of the blood into the body. The amount of blood it pushes out, compared to how much is in the heart, is the EF. This is calculated as a percentage. So if you had 100ml of blood in your heart and it pushes out say 60ml, then your EF is 60%. Normal is 55%-70% so your heart is still working fine. However, you can't really use EF as a guide to disease because you can have tons of plaque and still have a good EF. It just shows your heart is functioning well.