Heart Attack. Done With Angiography And Having Mild Chest Pains. Is It Necessary To For Surgery?

Question: Dear Dr,

My dad (56year old) had a heart attack. Angiography was done and has confirmed:
1) There are two arteries blocked. (a) Left Artery, just below the LAD, and (b) Right, quiet low down (after almost 3 intersections).
2) The Left atery is not significantly blocked and that right is the culprit.
3) The right artery is at least 90% blocked.
4) There is no evidence of muscle damange. The inferior wall is a bit lazy, but still alive.

The concern for Dr is that the blockage in the right artery is quiet low, and a challenging place to reach, and therefore conducting Angioplasty and placing stent(s) is a risk. CABG is not recommended because only one blockage is significant.

He has been on medical treatment (cholesterol control, BP, Blood thinning (tablet and claxane twice a day) for the past 3 weeks, and feels relatively stable. He was discharged for a few days. While he was discharged, Dr did not give any claxane. He had very mild chest pains after two days.

He is not diabetic nor hypertensive.

I can email Angio stills and Mibi report.

Would you suggest that he remain on Medical treatment or go through surgical treatment?

Thanks...

Regards