If a person is middle age or past, collateral circulation can adequately support cardiac tissue circulation in place of a partial or total blockage. It is usually fatal when a young man has a heart attack because he has not developed this collateral circulation. Usually young people who die of heart attacks are from clots or spasms, not progressive atherosclerosis. Interesting.
(I'm sure if i was 95% blocked in a major artery with symptoms, I would no doubt go for the stent)