Abstract Body (Do not enter title and authors here):
Background
Atrial fibrillation (AF) is a common cardiac arrhythmia associated with significant morbidity and mortality. Amyloidosis (AM) is characterized by the accumulation of amyloid protein in various anatomical sites, including the heart, atria, and ventricles. This amyloid infiltration leads to adverse chamber remodeling, predisposing patients to tachyarrhythmias such as atrial fibrillation/flutter. This study aims to re-evaluate the association of AM with AF by using the large nationwide inpatient database over a total duration of 5 years.

Methods
An analytical cross-sectional study was conducted utilizing the data from a survey-weighted national inpatient sample database covering admissions from Jan 2017 to Dec 2021. A total of 147,015,073 admissions of patients aged 18 years and above were included. Descriptive statistics and univariate logistic regression models were used to calculate prevalence rates and odds ratios (OR), respectively. The multivariate logistic regression model was then used to adjust various potential confounders, including age, gender, race, income, hypertension, diabetes, stage 3 or above chronic kidney disease (CKD), Charlson comorbidity index, and hospital-related factors.

Results
The 5-year prevalence of AF was 36.73% and 15.42% in admissions with and without AM, respectively. Significant differences between the with AM and without AM groups were in mean ages (72.40 vs. 58.08), female (41.83% vs. 56.92%), race of Black (24.57% vs. 15.40%), and CKD stage 3+ (44.83% vs. 16.65%), respectively. The univariate logistic regression analysis showed an OR for AF of 3.18 (95%CI: 3.102 - 3.267, P<0.000) in admissions with AM compared to those without. After adjustment for the potential confounders, the OR for AF decreased to 1.64 (95%CI 1.597- 1.686; P<0.000) in patients with Amyloidosis compared to those without.

Conclusion
This study confirms a significant association between amyloidosis and atrial fibrillation, demonstrating that patients with amyloidosis have a markedly higher prevalence of atrial fibrillation compared to those without. Univariate analysis showed an odds ratio of 3.18 for atrial fibrillation in amyloidosis patients, which remained significantly elevated at 1.64 after adjusting for confounders. These findings indicate the need for a comprehensive workup of suspected atrial fibrillation in amyloidosis patients. Further research should investigate the mechanisms behind this association and potential prevention.