Nationwide Trends in Hospitalizations for Atrial Fibrillation and Flutter in the United States before and during the Outbreak of the COVID-19 Pandemic

<b>Background/Objectives</b>: Atrial fibrillation (AF) and flutter (AFL) are the most common cardiac arrhythmias worldwide. Cardiovascular complications are a common manifestation of acute and post-acute COVID-19 infection. We aimed to analyze the nationwide trends in clinical characteristics and outcomes of patients hospitalized for AF/AFL before and during the COVID-19 outbreak in the U.S. <b>Methods</b>: This study is a retrospective analysis of patients, aged 18 and older, hospitalized for AF/AFL in the U.S. between 2016 and 2020. We drew data from the National Inpatient Sample (NIS) database. Baseline sociodemographic and clinical data, as well as outcomes including stroke, acute coronary syndrome (ACS), and mortality, were analyzed. Multivariable analysis was performed to identify independent associations between the different clinical and demographic characteristics and the composite endpoint of Mortality/ACS/Stroke. <b>Results</b>: An estimated total of 2,163,699 hospitalizations for AF/AFL were identified. The hospitalization volume between 2016 and 2019 was stable, averaging 465,176 a year, followed by a significant drop to 302,995 in 2020. Patients' median age was 72 years (IQR 62-80), 50.9% were male, and 81.5% were white. The composite endpoint steadily increased from 6.5% in 2016 to 11.8% in 2020 (P_trend < 0.001). In a multivariable regression analysis, age > 75 (OR: 1.35; 95% CI 1.304-1.399, <i>p</i> < 0.001), ischemic heart disease (OR: 1.466; 95% CI: 1.451-1.481; <i>p</i> < 0.001), and chronic kidney disease (OR: 1.635; 95% CI: 1.616-1.653; <i>p</i> < 0.001) were associated with the composite endpoint. COVID-19 was associated with the composite endpoint outcome in the year 2020 (OR: 1.147; 95% CI: 1.037-1.265; <i>p</i> = 0.007). <b>Conclusions</b>: Hospitalization for AF/AFL dropped significantly during the first year of the COVID-19 pandemic outbreak, possibly due to patients' avoidance of hospital visits. The composite endpoint of Mortality/ACS/Stroke uptrended significantly during the study period. COVID-19 was shown to be independently associated with the adverse composite outcome Mortality/ACS/Stroke.