Background Atrial fibrillation is a common comorbid condition among patients undergoing carotid endarterectomy (CEA) and carotid artery stent placement (CAS); however, the outcomes of patients with atrial fibrillation undergoing CAS have not been fully examined. We sought to investigate the impact of atrial fibrillation on outcomes of CEA and CAS in general practice. Methods We analyzed the data from the National Inpatient Sample (NIS), which is representative of all admissions in the United States from 2005 to 2009. The primary end point was postoperative stroke, cardiac complication, postoperative mortality, and composite of these end points. Univariate and multivariate regression analyses were performed to determine, first, the association of atrial fibrillation (compared to without atrial fibrillation) and, second, the association of CEA (compared with CAS) in patients with atrial fibrillation with the occurrence of postoperative stroke, cardiac complication, or death. Covariates included in the logistic regression were the patient's gender, age, race/ethnicity, comorbid conditions, and symptom status (symptomatic vs asymptomatic status) and the hospital's characteristics. Results Of the total 672,074 patients who underwent CAS or CEA, 8.8% (95% confidence interval [CI], 8.7-8.9) of the procedures were performed in patients with atrial fibrillation. Atrial fibrillation was associated with an increased risk of postoperative stroke in patients undergoing CEA (n = 879 [1.7%]; P <.0001; odds ratio [OR], 1.57; 95% CI, 1.32-1.86) but not in patients undergoing CAS. The relative risk of the composite end point of postoperative stroke, cardiac complications, and mortality was increased in patients with atrial fibrillation undergoing CAS (OR, 1.43; 95% CI, 1.18-1.74) and in those undergoing CEA (OR, 3.18; 95% CI, 2.89-3.49). After adjustment for potential confounders, the odds of the composite end point of postoperative stroke, cardiac complications, and mortality (OR, 1.31; 95% CI, 1.08-1.59) in atrial fibrillation patients were significantly higher among patients who underwent CEA (compared with those who underwent CAS). An opposite relationship was seen in patients without atrial fibrillation, in whom the composite end point was significantly lower in patients undergoing CEA. Conclusions Our analysis suggests that almost 10% of CAS and CEA is performed in patients with atrial fibrillation in general practice, and higher rates of adverse events are observed among these patients, particularly those undergoing CEA.