Because of the 9th century Myan POD, the Aztoltec Empire of this timelime would be different from the Aztec Empire of OTL .
First it should be noted that the "Aztec Empire" was a collection of competing tribes with a common culture but no real national identity. Individuals would consider themselves to be members of their tribe first, members of the Toltec culture second, and may not consider themselves to be members of an "Aztec Empire" at all.
The Mayan, Toltec, and Aztecs shared many gods and other cultural characteristics. The Aztoltecs (of ALT) would have the characteristics common to these mesoamerican empires. Also, for fun and convenience, I have assumed that an Aztec tribe created the island city of Tenochtitlan. From this defensible center they influenced the entire empire.
The peoples of this region did not have many natural checks to population growth in OTL. Unlike the Europeans, they did not suffer from serious diseases and their warfare had become ritualized. If you assume that the Aztec's massive level of human sacrifice was a cultural means to keep population under control then the a disease like papatlaca would lead to less of this sort of thing. So the Aztoltec Empire would cut out a lot fewer hearts than the Aztec Empire did.
Papatlaca would also probably slow down the development of the civilization.
- How much would development be slowed and what does that mean?
- What are common characteristics of Mesoamerican empires?