How successful are stents with "fully" blocked arteries?

Depends on vessel. Blocked arteries in neck are too risky to open if completely blocked. Vessels in legs are routinely opened after complete occlusion. Ask you doc about your particular situation.
Generally sucessful . Stents came on the medical scene around 1982 and have expanded the vascular lesions that can be treated. Generally short or focal vascular lesions are candidtes for stents. The wire must cross the lesion before the stent can be slid along the wire into position. You still need aggressive vascular medictions and monitoring.