Is It Safe To Take Prednisone For Polymyalgia Rheumatica?

A person was born with congential heart problems --- lots of them. Has had aorta mechanical surgery in 1998, carotid artery on one side., pace maker etc. Recently was told he has PMR and put on Prednidone of 20 mg. a day and then not tapered off -- abruptly stopped for nearly a week. Then put on 15 mg. for 4 weeks and 7-1/2 for four weeks...after taking the 7-1/2 mg. he ended up in the hospital .. he has had congestive heart failure 4 times in less than a month. Could this be related to the Prednisone not prescribed correctly?