How long does venous graft last?

In this video, Dr. OP. Yadava, Chief Executive Officer & Chief Cardiac Surgeon, National Heart Institute, New Delhi, talks about venous graft. The standard natural phases of venous grafts are three phases of occlusion: immediate which might be due to technical fault, fibro-endothelial hyperplasia might occur in 1 % of patients after a month. And last phase, is the atherosclerosis which happens over one year which can block the coronary artery as well the graft. Overall, approximately 50% of the venous grafts might get blocked over 10 years.