What do you recommend if I had a heart angiogram with 70% blockage in my left main coronary artery. No stint. Dr afraid he would block. Why?

Bypass surgery. everything is a balance between risk/benefit. often with a > 50% left main blockage, a bypass surgery is the safest choice. medical therapy alone carries a high risk of sudden death due to the severity of the blockage. a stent placement there, though relatively simple - might have a catastrophic outcome if any slight thing went wrong. a stent is indicated if surgery is higher than usual risk.