Atrial fibrillation can occur in the setting of severe sepsis, and often presents a therapeutic conundrum for critical care physicians, in that it can be relatively resistant to treatment until the sepsis has resolved, and its prognostic significance is unclear. A new study on a massive dataset shows atrial fibrillation in the setting of severe sepsis is associated with an increased risk of stroke and increased hospital mortality. Patients with severe sepsis who developed new-onset AF had a greater risk of in-hospital stroke than patients with preexisting AF and individuals without a history of AF.

Context New-onset atrial fibrillation (AF) has been reported in 6% to 20% of patients with severe sepsis. Chronic AF is a known risk factor for stroke and death, but the clinical significance of new-onset AF in the setting of severe sepsis is uncertain.

Objective To determine the in-hospital stroke and in-hospital mortality risks associated with new-onset AF in patients with severe sepsis.

Design and Setting Retrospective population-based cohort of California State Inpatient Database administrative claims data from nonfederal acute care hospitals for January 1 through December 31, 2007.

Patients Data were available for 3 144 787 hospitalized adults. Severe sepsis (n = 49 082 [1.56%]) was defined by validated International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 995.92. New-onset AF was defined as AF that occurred during the hospital stay, after excluding AF cases present at admission.

Main Outcome Measures A priori outcome measures were in-hospital ischemic stroke (ICD-9-CM codes 433, 434, or 436) and mortality.

Results Patients with severe sepsis were a mean age of 69 (SD, 16) years and 48% were women. New-onset AF occurred in 5.9% of patients with severe sepsis vs 0.65% of patients without severe sepsis (multivariable-adjusted odds ratio [OR], 6.82; 95% CI, 6.54-7.11; P < .001). Severe sepsis was present in 14% of all new-onset AF in hospitalized adults. Compared with severe sepsis patients without new-onset AF, patients with new-onset AF during severe sepsis had greater risks of in-hospital stroke (75/2896 [2.6%] vs 306/46 186 [0.6%] strokes; adjusted OR, 2.70; 95% CI, 2.05-3.57; P < .001) and in-hospital mortality (1629 [56%] vs 18 027 [39%] deaths; adjusted relative risk, 1.07; 95% CI, 1.04-1.11; P < .001). Findings were robust across 2 definitions of severe sepsis, multiple methods of addressing confounding, and multiple sensitivity analyses.
Conclusion Among patients with severe sepsis, patients with new-onset AF were at increased risk of in-hospital stroke and death compared with patients with no AF and patients with preexisting AF.

Incident Stroke and Mortality Associated With New-Onset Atrial Fibrillation in Patients Hospitalized With Severe Sepsis
JAMA. 2011 Nov 13. [Epub ahead of print]