Abstract Body (Do not enter title and authors here): Background: Atrial fibrillation is the most common cardiac arrhythmia in the United States. It is a tachyarrhythmia characterized by irregular electrical impulses in the atria. It poses a significant risk of stroke and is a major concern in cardiovascular health. Understanding mortality trends related to AF across racial groups is crucial for guiding targeted treatment strategies, particularly for marginalized populations.

Methods: Data were obtained from the CDC WONDER database. Age-adjusted mortality rates for atrial fibrillation and flutter between 1999-2022 were calculated relative to the standard US population. Time trends were assessed using annual percentage change (APC) and average APC (AAPC), employing Joinpoint Regression Software (version 8.4.2, NCI). Monte Carlo permutation analysis was utilized to determine the most parsimonious trend.
Results: In 2022, atrial fibrillation and flutter caused 28,932 deaths in the United States. Analyzing mortality trends from 1999 to 2022 across all racial groups revealed a significant increase in the average annual percentage change (AAPC) of 3.6% (95% CI 3.1-4.2, p <0.001), with mortality rates rising from 4.8 to 10.6 deaths per 100,000. Breakdown by race indicated AAPC increases of 4.0% among non-Hispanic whites, 3.9% among non-Hispanic blacks, and 3.7% among Hispanics.
Among non-Hispanic whites, two distinct periods of change were observed: an APC of 4.9% (95% CI 4.5-5.4, p <0.001) from 1999-2015 and an APC of 1.8% (95% CI 0.2-3.4, p <0.001) from 2015-2022. For non-Hispanic blacks, the mortality trend remained uniform, with an APC of 3.9% from 1999-2022. Hispanics displayed two join points: an APC of 4.6% (95% CI 4.0-5.3, p <0.001) from 1999-2016 and an APC of 1.1% (95% CI -2-4.3, p=0.5) from 2016-2022.

Conclusion:
In conclusion, our study highlights significant increases in mortality rates attributed to atrial fibrillation and flutter across all racial groups in the US from 1999 to 2022. Non-Hispanic whites exhibited a slowdown in the rate of increase between 2015 and 2022, contrasting with uniform trends among non-Hispanic blacks and fluctuating patterns among Hispanics. These findings emphasize the importance of tailored interventions to address racial disparities in mortality rates associated with atrial fibrillation and flutter, particularly targeting areas where trends deviate from the overall trajectory. Further research should explore the underlying cause for these observed disparities in outcome.