Patients in the device group demonstrated lower rates of both cardiovascular mortality ( 1.0 events per 100 patient-years for the device group [ 17/463 patients , 3.7 % ] vs 2.4 events per 100 patient-years with warfarin [ 22/244 patients , 9.0 % ] ; hazard ratio [ HR ] , 0.40 ; 95 % CI , 0.21-0 .75 ; P = .005 ) and all-cause mortality ( 3.2 events per 100 patient-years for the device group [ 57/466 patients , 12.3 % ] vs 4.8 events per 100 patient-years with warfarin [ 44/244 patients , 18.0 % ] ; HR , 0.66 ; 95 % CI , 0.45-0 .98 ; P = .04 ) .