1
general::
Also, hard on the heels of. Directly behind, immediately following, as in Mom's birthday comes on the heels of Mother's Day, or Hard on the heels of the flood there was a tornado. The hard in the variant acts as an intensifier, giving it the sense of "close on the heels of". [Early 1800s] Also see AT ONE'S HEELS.
American Heritage Idioms
2
general::
Phrase(s): on the heels of something
Fig. soon after something. • There was a rainstorm on the heels of the windstorm. • The team held a victory celebration on the heels of their winning season.
McGrawhill's American Idioms And Phrasal Verbs