Isolazine for CKD patient. Be stopped?

Dear Doctors, my father is 76 years old now and he  was diagnosed with triple vessel coronary artery disease with lmca disease 3 years before. He had angioplasty procedure to keep stent in one of the major artery block and cardiologist advised to mange the other 2 100% blocks via medical management. Unfortunately after the angioplasty procedure his kidney got affected and his creatine level was 1.6. Till now, almost 3 years almost he managed his creatine level 1.6-1.8 by following strict diet. Recently the cardiologist changed the medicine to improve his heart function. He was given Isolazine and his blood pressure got increased and one of his legs got swollen. Not sure if the fluid retention is because of kidney or heart issue. Is Isolazine safe for kidney patients? Should it be stopped? He has taken the medicine for four months now. Please advise. Many thanks in advance.