Your sentence is an example of syntax called fronting. Peters in the section on fronting in The Cambridge Dictionary of English Grammar (p135) states:
In conversation, fronting of the clausal object or complement may be
achieved simply by promoting it to the start of the clause, as in:
- Raw egg for breakfast I can't stand.
- Wonderful it was indeed!
You'll note that neither the object (raw egg for breakfast) nor the complement (wonderful) is separated from the rest of the sentence by a comma. But as the comments under your question indicate, this is not a matter of grammaticality. The comma is acceptable to emphasise the this and represent a small pause.
Note that there is a related example of fronting (called left-dislocation) where a comma is needed. Namely, when the sentence contains a resumptive pronoun. Peters has the example:
- The last owner, I heard he had moved overseas.
Without the comma the reader or listener is momentarily led down a garden path.