Abstract Body (Do not enter title and authors here): Introduction
While the respiratory symptoms of COVID-19 have been shown to contribute to poor outcomes, there is growing evidence that cardiovascular complications also contribute significantly to these outcomes. Hypoxia, inflammatory effects, and autonomic dysregulation associated with COVID-19 may predispose patients with underlying cardiovascular conditions to more severe infections. Among cardiac arrythmias, atrial fibrillation is the most common arrythmia and has been associated with increased risk in this patient population. There remains a need to examine in-hospital outcomes in these patients.

Methods
Patients admitted for COVID-19 infection were identified using the 2021 National Inpatient Sample (NIS). Patients were stratified based on the presence chronic atrial fibrillation. Logistic and linear regression models were used for analysis, adjusting for confounding variables using the Charlson comorbidity index. A univariate screen with a p-value cutoff of less than 0.2 was performed followed by a multivariate analysis. The threshold for statistical significance was set at a 2- tailed p-value of 0.05.

Results
Of the patients admitted with a primary diagnosis of COVID-19 in 2021, mortality was higher for patients with atrial fibrillation (aOR 1.76, 95% CI 1.71-1.83). Compared to the Caucasian population, the Hispanic (aOR 1.25, 95% CI 1.19-1.31), Asian (aOR 1.14, 95% CI 1.05-1.23), and Native American (aOR1.36, 95% CI 1.19-1.56) populations had higher odds of mortality. Females with atrial fibrillation had lower mortality compared to men (aOR 0.76, 95% CI 0.74-0.78). Additionally, the study population had higher odds of vasopressor use (aOR 1.77, 95% CI 1.60-1.96), mechanical ventilation (aOR 1.82, 95% CI 1.75-1.89), and renal replacement therapy (aOR 1.61, 95% CI 1.52-1.72). They had higher total hospital charges (aOR 24270, 95% CI 21676.33-26864.24) and length of stays (aOR 1.15, 95% CI 1.02-1.28).

Conclusions
This study highlighted differences in mortality, in-hospital outcomes, charges, and length of stay in patients with concurrent atrial fibrillation and COVID-19. These findings may be explained by the hypercoagulability, myocardial stress, and systemic inflammation associated with these conditions. Complicated management strategies including anticoagulation may also contribute to worse outcomes. Additionally, this study highlighted racial and gender disparities that all clinicians need to be mindful of when providing equitable care.