Atrial Fibrillation Following Out-of-Hospital Cardiac Arrest and Targeted Temperature Management—Are We Giving It the Attention it Deserves?*

Objectives: Atrial fibrillation has been associated with increased mortality in the general population and mixed populations of critical ill. Atrial fibrillation can also affect patients during post–cardiac arrest care. We sought to assess the prognostic implications of atrial fibrillation following out-of-hospital cardiac arrest, including relation to the level of targeted temperature management. Design: A post hoc analysis of a prospective randomized trial. Setting: Thirty-six ICUs. Patients: We included 897 (96%) of the 939 comatose out-of-hospital cardiac arrest survivors from the targeted temperature management trial (year, 2010–2013) with data on heart rhythm on day 2. Interventions: Targeted temperature management at 33°C or 36°C. Measurements and Main Results: Endpoints included cumulative proportion of atrial fibrillation following out-of-hospital cardiac arrest and 180-day all-cause mortality and specific death causes stratified by atrial fibrillation. Atrial fibrillation on day 2 was used as primary endpoint analyses to exclude effects of short-term atrial fibrillation related to resuscitation and initial management. The cumulative proportions of atrial fibrillation were 15% and 11% on days 1 and 2, respectively. Forty-three percent of patients with initial atrial fibrillation the first day were reported with sinus rhythm on day 2. No difference was found between the groups treated with targeted temperature management at 33°C and 36°C. Patients affected by atrial fibrillation had significantly higher 180-day mortality (atrial fibrillation: 66% vs no-atrial fibrillation: 43%; p logrank < 0.0001 and unadjusted hazard ratio, 1.75 [1.35–2.30]; p < 0.0001). The association between atrial fibrillation and higher mortality remained significant (adjusted hazard ratio, 1.34 [1.01–1.79]; p < 0.05) adjusted for potential confounders. Atrial fibrillation was independently associated with increased risk of cardiovascular death and multiple-organ failure (adjusted hazard ratio, 2.07 [1.39–3.09]; p < 0.001), whereas no association with higher risk of death from cerebral causes was found. Conclusions: Atrial fibrillation was independently associated with higher mortality, primarily driven by cardiovascular causes and multiple-organ failure, and may thus identify a vulnerable subpopulation. Whether treatment to prevent atrial fibrillation is associated with an improved prognosis remains to be established.