New-Onset Atrial Fibrillation Is an Independent Predictor of Mortality in Medical Intensive Care Unit Patients

Background: Atrial fibrillation (AF) has been extensively studied in postoperative critically ill surgical patients, but little literature exists to describe the outcomes of patients in the medical intensive care unit (ICU). Objectives: To determine the incidence of new-onset AF in patients admitted to a medical ICU and if new-onset AF was associated with adverse clinical outcomes. Methods: This was a single-center, retrospective study of all adult patients admitted to the medical ICU at an academic medical center for >24 hours between December 2008 and April 2010. Collected data included past medical history, incidence of new-onset AF, Acute Physiology and Chronic Health Evaluation II scores, organ failure, length of stay in the ICU and hospital, and in-hospital and 60-day survival. Results: A total of 741 patients were included. New-onset AF occurred in 53 patients (7.2%). In-hospital mortality was significantly greater for patients with new-onset AF (45% vs 16%; adjusted odds ratio [OR] = 2.21, 95% CI 1.07-4.54, P = 0.032), as was 60-day mortality (51% vs 23%; adjusted OR = 1.99, 95% CI = 1.01-3.91, P = 0.047). Patients with new-onset AF experienced greater ICU (6 +/- 10.2 days vs 3 +/- 3.6 days, P < 0.01) and hospital (15 +/- 19 days vs 7 +/- 9 days, P < 0.01) lengths of stay. Conclusions: Medical ICU patients who developed new-onset AF experienced a 2-fold increase in the odds of in-hospital mortality and death at 60 days. Further research investigating contributing factors to new-onset AF and potential treatments is warranted.