A lot if factors come in to play when deciding if stents are the correct approach to the blockages. To place a stent, a guide wire must first be passed from the Femoral artery or Radial artery up to the heart and down the coronary arteries. If the blockages are too severe or the arteries are too tortuous (twisty) the wire may not be able to pass. And sometimes, even if they are able to pass the guide wire, they may not be able to get the stent through. A stent is basically chicken wire (on a smaller scale) that is passed into the blockage and a balloon is inflated, which expands the stent and leaves it behind once the balloon is deflated/removed).
Also, the lengths of the blockages may be too much. You say he has seven blockages but it may take more than seven stents. Each blockage may take 2,3, or even 4 stents if there are long segments of the blocked arteries.
Additionally, with diffuse disease, coronary artery bypass grafting (CABG) will be the longer term fix. Stents have the ability to occlude again, and sometimes at a very rapid rate. So if the first stent in a line if six stents gets occluded again, all the downstream stents aren't doing a bit if good.
Bypass grafting will use the Greater Saphenous Vein from his leg as well as either one or two arteries from his chest wall. This has a longer lasting effect because it is all his own tissue being used. And the recovery rates are pretty quick. 1-2 nights in ICU. 2-3 days in a step down unit. Home in 6-7 days, maybe even less.
TL,DR:
Sometimes stents just won't cut it
Grafting can give better revascularization and is better for the longer term.
Perfusionist.