The 2-year incidence of ST in the EES group ( 1 % ; 95 % CI : 0.4 to 2.2 ) was similar to that in the ZES-S group ( 1.4 % ; 95 % CI : 0.7 to 2.8 ) , whereas it was lower compared with the PES ( 4.6 % , 95 % CI : 3.1 to 6.8 ) and BMS ( 3.6 % ; 95 % CI : 2.4 to 5.6 ) groups ( chi-square = 16.9 ; p = 0.0001 ) .