Post BYPASS surgery and ANGIOGRAM Reports

hello. My dad had a bypass surgery last year. he had 3 blockages. main arteries were blocked. after the by pass surgery within two months time we got an ct angio done and the blockages reappeared, recently last month we got an angiogram done. my giving you the details of the final diagnosis report and want your help and wants to know what has been revealed. is the situation very critical. what do i do next.
FINAL DIAGNOSIS: CAD with native single vessel disease, LIMA to LAD and LIMA to RIMA Y graft-patent, LIMA to RIMA Y graft to PDA occluded, impaired LV function.

Please help me.