You can also use this, which might be a few milliseconds faster, since getObject() returns null on failure:
I would use $tvr for the variable name since you're not really getting the TV object (though it's pretty obvious that you're not).
I think if you set the TV to its default value, the TVR will be removed the first time you save the TV. (I could be wrong).
If the TV requires other fields (e.g., list, image, etc.) creating the TVR without them isn't going to work unless they already exist in the TV object.
I use this method all the time, because it's very fast, but only for TVs that only need a raw value stored (which applies to almost all my TVs).