RESULTS: There were a total of 72 patients evaluated, 32 PrBC patients and 40 AfBC patients. Of these, 55% were male (p=0.7), mean age 66 years (p=0.2). Nonvalvular AF was the indication for OAC in 75% of these patients (p=0.09) with a mean CHADS of 2.3 (p=0.1). The predominant CIED procedure was original pacemaker insertion in 58% of patients (p=0.3). There were no significant difference withbaseline INR (p=0.4). The peri-procedure INR differed significantly, 1.4 in PrBC and 1.9 in AfBC (p<.001, 95% CIs [1.35, 1.53] and [1.76, 2.02] respectively). All cases were successful with significant bleeding or thromboembolic events in either group. The PrBC group had significantly higher use of pre-operative reversal agents, predominantly vitamin K, as compared to the AfBC group (0.53 v 0.14, p<.001, 95% CIs [0.36, 0.70] and [0.04, 0.24] respectively). No blood products were used to reverse any of these patients. By 10 days post operation, the AfBC patients were three times more likely to achieve a therapeutic INR (p<.001) with a mean 10 day post-operative INR of 1.8 in the PrBC group and 2.4 in the AfBC group (p<.001, 95% CIs [1.36, 2.20] and [2.20, 2.60] respectively).