New-Onset, But Not Chronic Atrial Fibrillation, Is a Significant Factor Contributing to Mortality Among Patients with Severe COVID-19.

BACKGROUND Atrial fibrillation (AF) is a common arrhythmia in the general population and the most frequently presented arrhythmia in the intensive care unit. We investigated the effects of AF on the outcomes of critical COVID-19 patients, especially focusing on differences between chronic (CAF) and new-onset AF (NOAF) during critical disease. MATERIAL AND METHODS In this case-control study, we investigated the association of CAF and NOAF as an exposure, with in-hospital mortality as an outcome. We identified 2 patient groups, NOAF and CAF, which were compared with controls (all other hospitalized patients with critical COVID-19 pneumonia). No specific selection or matching was performed. The chi-square test was used for categorical variables; t test and Mann-Whitney U tests were used for continuous variables, depending on distribution. P<0.05 was considered significant. RESULTS In-hospital mortality was significantly higher in the NOAF group, while in the CAF group, it was similar to that of the control group. The NOAF group had significantly higher markers of inflammation and more severe acute respiratory distress syndrome (ARDS), measured with computed tomography. NOAF was strongly associated with in-hospital death, with OR 6.392 (95% CI, 2.758-14.815), P<0.000. In comparison, the CAF group was older and had more cardiovascular comorbidities, with similar markers of inflammation and severity of ARDS as the control group. CONCLUSIONS NOAF in COVID-19 was linked with significant risk of death, being a sign of extreme cardiac, pulmonary, and metabolic instability. NOAF should be considered as an important marker of instability and predictor of poor outcomes among patients with COVID-19.