RenalRisk factors and outcomes associated with new-onset atrial fibrillation during acute respiratory distress syndrome☆,☆☆
Introduction
Atrial fibrillation (AF) is the most common arrhythmia to affect the critically ill, with an estimated incidence of 8% to 10% among intensive care patients [1], [2]. New-onset AF among critically ill patients may be associated with poor outcomes, for example, patients with severe sepsis who develop new-onset AF have increased short-term [3] and long-term [4] risks for stroke and death. New-onset AF during critical illness may potentially be on the etiologic pathway to mortality through hemodynamic compensation [5] or thromboembolic complications; [3] alternatively, new-onset AF may merely be a marker of increased severity of illness. Few studies have prospectively identified new-onset AF during critical illness and assessed outcomes in the context of baseline illness severity.
Unfortunately, optimal management strategies for AF during critical illness are unclear [6]. Insights into mechanisms of AF during critical illness may enable a more rational approach to prediction, prevention, and treatment. Prior studies using population-based [2], [3], single-center [7], [8], [9], or trial [10] data have shown that acute factors (eg, choice of vasopressor, acute organ failures, mechanical ventilation, and right heart catheterization), rather than preexisting cardiovascular comorbidities [11], [12] are associated with increased risk for new-onset AF during critical illness. Thus, new-onset AF during critical illness may have different underlying mechanisms as compared with AF that develops in the community. However, triggers of new-onset AF during critical illness are poorly understood. Potential contributing factors have been hypothesized to include autonomic activation, inflammation, atrial stretch, and/or myocardial injury [13].
We conducted an exploratory post hoc analysis to investigate outcomes and risk factors associated with new-onset AF during ARDS using data prospectively collected during the multicenter ARDS Network Albuterol for Treatment of Acute Lung Injury (ALTA) trial [14]. We investigated the hypothesis that new-onset AF is associated with increased risk of death among patients with ARDS after adjusting for baseline severity of illness. To better understand potential mechanisms for new-onset AF during critical illness, we also investigated the hypothesis that increased baseline epinephrine, interleukin 6, interleukin 8, central venous pressure, and troponin (surrogate measures for autonomic activation, inflammation, atrial stretch, and myocardial injury, respectively) would be associated with incident AF.
Section snippets
Data source
We used data from the ALTA trial, which enrolled 282 patients with ARDS and randomized 152 to nebulized albuterol and 130 to nebulized saline placebo to determine the effect of albuterol treatment on outcomes over 90 days. Patients were enrolled within 48 hours of ARDS onset. Further details regarding patient selection, definitions, and study protocol used in ALTA can be found in the original manuscript (www.clinicaltrials.gov; registry no. NCT00434993) [14]. Briefly, the ALTA investigators
Results
Of the 282 patients with ARDS enrolled in ALTA, 28 (10%) had new-onset AF, and the median duration of AF was 1.5 days (interquartile range, 1-2). As previously reported [14], AF incidence did not differ by ALTA trial albuterol randomization group. Patients had a mean age of 51.6 years, 45% were women, and 77% were white. Table 1 demonstrates similar demographics, APACHE scores, and hemodynamic parameters regardless of AF status. We did not identify associations between new-onset AF and a
Discussion
We investigated risk factors and outcomes associated with the development of new-onset AF among patients with ARDS. Patients with new-onset AF in the setting of ARDS had higher 90-day mortality, which persisted after adjustment for baseline APACHE III scores. We did not find evidence to support our hypothesis for increased baseline inflammation (interleukin 6 and interleukin 8), atrial stretch (CVP), myocardial injury (troponin), or catecholamine activation (epinephrine) among patients who
Conclusion
In a secondary analysis of clinical trial data among patients with ARDS, we found that patients with new-onset AF during ARDS had higher APACHE-adjusted mortality. We did not identify associations between hypothesized markers for acute inflammation, myocardial injury, or autonomic activation and subsequent incidence of AF. Our study provides additional evidence that new-onset AF during critical illness is associated with poor outcomes. However, risk factors and mechanisms for the development of
Acknowledgments
We would like to thank the ARDS Network Natural History Committee and Steering Committee for their oversight of our project.
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Cited by (0)
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Author contributions:
DBA: statistical analysis, interpretation of findings, and drafting manuscript.
EJB: revising manuscript for intellectual content.
EKB and KAH: biomarker analysis.
AJW: conceptualizing study, statistical analysis, and revising manuscript for intellectual content.
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Sources of support: National Institutes of Health/National Heart Lung and Blood Institute K01HL116768-01 (Walkey) and 2R01HL092577 (Benjamin); ClinicalTrials.gov identifier: NCT00434993.