New-onset atrial fibrillation in critically ill patients and its association with mortality: A report from the FROG-ICU study.

Background: Atrial fibrillation (AFib) is associated with adverse outcome in critical illness, but whether this effect is independent from other risk factors remains uncertain. New-onset AFib during critical illness may be independently associated with increased in-hospital and long-term risk of death.

Methods: FROG-ICU was a prospective, observational, multi-centre cohort study designed to investigate the outcome of critically ill patients. Inclusion criteria were invasive mechanical ventilation and/or treatment with a positive inotropic agent for >24 h. Heart rhythm was assessed at inclusion and during ICU stay with digital ECG recordings. Among patients who had AFib during ICU stay, new-onset and recurrent AFib were diagnosed in patients without and with previous history of AFib, respectively. Primary endpoint was in-hospital mortality; secondary endpoint was 1-year mortality among ICU survivors.

Results: The study included 1841 critically ill patients. During ICU stay, AFib occurred in 343 patients (19%). New-onset AFib (n = 212) had higher in-hospital mortality compared to no AFib (47 vs. 23%, P < 0.001) or recurrent AFib (34%, P = 0.032). New-onset AFib showed increased risk of in-hospital death after multivariable adjustment compared to no AFib (OR 1.6, P = 0.003) or recurrent AFib (OR 1.8, P = 0.02). Among the 1464 ICU-survivors, new-onset AFib during ICU stay showed higher post-ICU risk of death compared to no AFib (HR 2.2, P < 0.001). After multivariable adjustment, new-onset AFib showed higher post-ICU risk of death compared to no AFib (HR 1.6, P = 0.03).

Conclusion: New-onset AFib is independently associated with in-hospital and post-ICU risk of death in critically ill patients.