Being consumed by worms connotes losing even what little substance the dead (Babylon) temporarily possessed after death.
Comparison: The Book of Mormon adds a phrase (here bolded) to the King James Version: “Thy pomp is brought down to the grave, and the noise of thy viols is not heard: the worm is spread under thee, and the worms cover thee” (Isa. 14:11). The meaning remains the same but is clearer with the addition.
The NIV also improves the reading of this passage but does so with a different structure: “All your pomp has been brought down to the grave, along with the noise of your harps.” The parallel between pomp and harps is completed by being “brought down to the grave.” The “and” is italicized in the King James Version, indicating that it is a translator’s solution to a grammatical/literary assumption in the Hebrew. The NIV solves that assumption with another addition; “along with.” The Book of Mormon is just another mode of making sense of the passage in English. Tvedtnes notes that none of the Isaiah manuscripts contains a variant supporting the Book of Mormon reading.