Pitt will return to Melbourne with his family to seek further opinions on the initial diagnosis.
The club did not release any further details about the nature of the heart irregularity.
"The club will be working closely with Jayden, his family and his management to determine the best course of action for his future," Fremantle football operations manager Chris Bond said in a statement released on Tuesday night.
"In the meantime, training and playing football for Jayden have been put on hold while further opinions are sought."
The 20-year-old has played 10 games since being recruited with pick No.20 in the 2010 NAB AFL Draft.
Fremantle have a bye this weekend after opening their season with a 28-point win over arch rivals West Coast.
