The 24-month primary patency rates in the VIABAHN ( ) and BMS group were : intention-to-treat 63.1 ( 95 % CI 0.52-0 .76 ) versus 41.2 % ( 95 % CI 0.29-0 .57 ; log rank p = 0.04 ) and TPP 69.4 ( 95 % CI 0.58-0 .83 ) versus 40.0 % ( 95 % CI 0.28-0 .56 ; log rank p = 0.004 ) .