It is possible to stent a completely occluded vessel in some cases. The procedure involves a guide wire attached to the cath, and if the guide can penetrate the plaque, some of the plaque can be removed by a grinding instrument.
It is possible a 100% blocked vessel has other vessels supplying the deficit area and that may be sufficient.
My mom was 100% blocked in her left main artery and the doctors were successful in putting a stent in that artery. Make sure that your doctor has done many of these procedures.