The guidelines are to stent a >70% blocked artery if there is pain (angina) that cannot be controlled with medication. I have a totally blocked LAD (collateral vessels provide a natural by-pass) and a circumflex blockage of 72%. I have been treated with medication for the past 4 years and do not experience any angina unless I engage in vigorous exercise...then nitrate medication relieves the angina.
The consequences of treating with medication or an interventional procedure (stent or by-pass) has the same long-term outcomes. Meaning intervention does not increase longivity. The COURAGE study has made that conclusion based on long-term studies and follow up.