Impact of New-Onset Atrial Fibrillation on Mortality in Critically Ill Patients

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in critically ill patients and significantly impacts mortality. This study sought to evaluate the impact of new-onset AF on mortality in a critically ill population. This study identified 48018 adult patients admitted to the ICU from the Medical Information Mart for Intensive Care (MIMIC)-IV database. Patients were categorized as no AF, pre-existing AF, or new-onset AF. We analyzed mortality at 3 months, 6 months, and 1 year. Overall, 31,562 (65.73%) patients had no AF, 4877 (10.16%) had pre-existing AF, and 11,579 (24.11%) had new-onset AF. Median ages were 61.47 years (no AF), 76.12 years (pre-existing AF), and 75.26 years (new-onset AF). New-onset AF was associated with the highest mortality rates: 25.16% at 3 months, 29.23% at 6 months, and 34.04% at 1 year, compared to 17.94%, 22.55%, and 28.52% for pre-existing AF, and 14.54%, 17.25%, and 20.69% for no AF respectively (p < 0.001 for all). Multivariate Cox regression indicated that new-onset AF significantly increased the risk of 1-year mortality by 15.5% compared to no AF (HR: 1.155, 95% CI: 1.101-1.212; p < 0.001) and by 23.9% compared to pre-existing AF (HR: 1.239, 95% CI: 1.164-1.318; p < 0.001). Kaplan-Meier analysis confirmed lower survival probabilities for new-onset AF over one year compared to the other groups (p < 0.001). In patients with critical illness, new-onset AF is associated with an increased risk of mortality compared with pre-existing AF or no AF.