something going on even without objective noninvasive testing findings or blood work.
it also takes an IV and 10-12 minutes to do so it's not a huge deal (not cracking the chest)
We also do it in the crazies or those who go to the ER once a week... where the ER doc admits them for recurrent expensive workups just to prove to everyone including the patient (and other doctors) that they don't have anything going on.
If anything our noninvasive tests are absolute garbage (stress tests) in predicting badness or bad outcomes.. So unless the blood work clearly rules you in, than you truly don't know. Though most of the time if the story isn't concerning than we do try and limit the invasive stuff.