The tension in the hospital when Liam brought Casper wasn't fake. Casper did go through many tests to find the cause of his concussion and to eliminate the possibility of strokes or other health issues.
Although doctors assured Casper that he just needs proper rest and food for his body, Casper didn't take his health lightly. However, he chose to fake his heart attack so that if Anya manages to hold onto something against him, he could make use of medical records.
Did he have another choice?
No. Anya was like a monster in her field. One needs to fear her to stand against her. So he had to focus on saving himself first.
He was definitely not a fool. Thus he knew the trouble he pulled on himself. Trying to save himself from the laws, he gave an open chance for Alvin to use his health against him.