Atrial Fibrillation in Critically Ill Patients: Incidence and Outcomes.

BACKGROUND: Atrial fibrillation (AF), either chronic or new onset, is common in critically ill patients. Its epidemiology and relationship with clinical outcomes are poorly known.

OBJECTIVE: To understand the burden of AF in patients admitted to the ICU and its impact on patients' outcomes.

METHODS: This is a single-center, retrospective cohort study evaluating all patients with AF admitted to a non-cardiac intensive care unit over the course of 54 months. Clinical outcomes were evaluated in the short (hospital discharge) and long term (two-year follow-up). The hazard ratio (HR) with 95% CI was computed for the whole population as well as for propensity score-matched patients, with or without AF.

RESULTS: A total of 1357 patients were screened (59.1% male), with a mean age of 75 ± 15.2 years, length of intensive care unit stay of 4.7 ± 5.1 days, and hospital mortality of 26%. A diagnosis of AF was found in 215 patients (15.8%), 142 of whom had chronic AF. The hospital all-cause mortality was similar in patients with chronic or new-onset AF (31% vs. 28.8%, p = 0.779). Patients with AF had higher in-hospital, one-year, and two-year crude mortality (30.2% vs. 22.9%, p = 0.024; 47.9% vs. 35.3%, p = 0.001; 52.6% vs. 38.4%, p < 0.001). However, after propensity score matching (N = 213), this difference was no longer significant for in-hospital mortality (OR: 1.17; 95% CI: 0.77-1.79), one-year mortality (OR: 1.38; 95% CI: 0.94-2.03), or two-year mortality (OR: 1.30; 95% CI: 0.89-1.90).

CONCLUSIONS: In ICU patients, the prevalence of AF, either chronic or new-onset, was 15.8%, and these patients had higher crude mortality. However, after adjustment for age and severity on admission, no significant differences were found in the short- and long-term mortality.