Well, assuming they are using therapeutic hypothermia (standard protocol) for 48 hours post-arrest, it's probably already happening. A combination of EEG (brain wave test for electrical activity and quality thereof) and CT or MRI to look for swelling and blood flow. There are a number of other tests as well that you would not want to know about.
The fact that they were able to get a heartbeat back (ROSC- return of spontaneous circulation) is encouraging for physiological survival -it points to high-quality CPR having been performed. Neurological damage has almost certainly occurred however. So the over-arching issue at this point is quality of life.