Abstract Body:
Background
Carotid artery stenting (CAS) and carotid endarterectomy (CEA) are two types of carotid revascularization procedures performed on symptomatic patients. Frequently, carotid artery stenosis is found during stroke workup and these patients undergo revascularization during the same nonelective admission. Conversely, revascularization can be postponed in the acute setting and patients undergo the procedure in a subsequent elective admission. Hospital readmission rates can help identify the optimal strategy to minimize post-procedural complications. The purpose of this study is to analyze 30-day readmission rates in elective and nonelective CAS and CEA procedures.

Methodology
The 2017 National Readmission Database is queried for hospital admissions for CAS and CEA procedures. All admissions are stratified into elective and nonelective hospitalizations. A total of 5045 elective CAS, 29317 elective CEA, 3553 nonelective CAS, and 8491 nonelective CEA procedures are analyzed for a subsequent non-elective 30-day readmission.

Results
There is a significantly lower 30-day readmission rate in elective CAS relative to CEA (4.8% vs 5.6%, P<0.001), while there is no such difference between nonelective CAS and CEA (10.6% vs 10.3%, P=0.582). Comorbidities such as PAD, depression, and other mental health disorders predict readmission after elective CAS, while heart failure, AKI, CAD, COPD, CKD, lipid disorders, DM, obesity, anemia, cancer, and dementia are predictive after elective CEA. CVA/TIA, respiratory failure, and substance abuse predict readmission for both elective carotid revascularization procedures. Likewise, comorbidities such as COPD, substance abuse, lipid disorders, liver failure, and cancer predict readmission after nonelective CAS, while AKI, respiratory failure, DM, GI bleeding, and anemia are predictive after nonelective CEA. Heart failure, CKD, and liver failure predict readmission in both nonelective carotid revascularization procedures.

Conclusion
In this retrospective observational study, certain comorbidities increase the likelihood of readmission after carotid revascularization procedures. In conclusion, the most frequent etiology of readmission for elective procedures is cardiac complications, e.g. heart failure and myocardial infarction, while the most frequent source for nonelective procedures is neurological complications, e.g. CVA/TIA. This data provides further insight into the risks involved in carotid revascularization procedures.