My Father Is 77 Years Old And Has Diabetes From

My Father is 77 years old and has diabetes from the past 20 years.He always has controlled sugar levels with medicine and has a history of hypoglyacaemia.Recently while getting prepared for his knww surgery the dr advised angiography and he was diagnosed with Left main: Normal, LAD:shows 70% priximal occlusion and another 70-80% ostail and proximal occlusion.
LCX:Normal, OM1 and OM2 Normal
RCA:shows 95% mid segment occlusion and heavy calcification,PD shows 50% mid segment stenosis,PLV normal,LIMA:shoot not done,lview of heavy aortic knuckle and aortic calcification.
Can you pls suggest the most minimally invasive treatment for this.