Original ContributionInitial hyperlactatemia in the ED is associated with poor outcome in patients with ischemic stroke
Introduction
In the United States, approximately 8% of ischemic strokes result in death [1]. Accordingly, it is important to identify accurate predictors of outcome after ischemic stroke. Although a clinical prognostic scoring model has been designed and validated [2], there are still research efforts to identify prognostic factors among laboratory markers related to inflammation, hemostasis, neuronal or glial injury, and cardiac dysfunction [3].
Hyperlactatemia is considered a marker of the metabolic stress response and is associated with increased mortality in critically ill patients [4], [5], [6]. In several previous studies using magnetic resonance spectrometry and microdialysis, lactate has been shown to accumulate in ischemic brain lesions among patients with acute stroke [7], [8], [9]. Recently, Brouns et al [10] demonstrated that the cerebrospinal fluid (CSF) lactate level is a reliable marker for metabolic crisis in acute ischemic stroke or transient ischemic attack and is associated with long-term outcomes. Although Brouns et al failed to show an association between blood lactate level and poor outcome, their study lacked the power to demonstrate negative conclusions, given the heterogeneity of the study sample.
As such, in the present study, we aimed to determine whether hyperlactatemia is associated with poor outcome and/or death in patients with ischemic stroke.
Section snippets
Study design
This retrospective observational study was approved by the institutional review board of the host hospital, and a waiver for informed consent was obtained. The study was conducted at a 1000-bed urban academic tertiary care hospital with an annual emergency department (ED) census of 35 000. Patients were initially evaluated by ED physicians and then by neurology attending physicians.
Between April 1, 2010, and March 31, 2011, all consecutive patients admitted via the ED with an admission
Baseline characteristics
Data from baseline demographics, risk factors, and stroke diagnosis are presented in Table 1. The mean subject age was 68.6 ± 12.2 years, with men comprising a larger proportion of the study cohort (58.2%). The mean time from stroke onset to ED arrival was 11.8 ± 17.3 hours, whereas the mean initial NIHSS score was 5.9 ± 6.1. In total, 64 patients (21.9%) received intravenous thrombolysis, and transfemoral cerebral angiography (TFCA) was performed in 67 patients (22.9%). Initial lactate levels
Discussion
Our results demonstrate that after adjusting for potential confounders, patients with lactate levels greater than 2 mmol/L at the time of initial presentation to the ED have an increased risk of poor outcome at 3 months. To our knowledge, this is the first report to detect an association between hyperlactatemia and poor outcome in patients with ischemic stroke.
Lactate is a known by-product of anaerobic metabolism and is elevated in hypoperfusion states. Specifically, lactate accumulates when
Limitations
The results of this study must be interpreted in the context of the study limitations. This study represents a retrospective observational study performed in a single center without any controls. Although we adjusted for known confounders, we could not completely exclude the residual effect of confounding. Moreover, the prestroke functional status of enrolled patients was not available. We also did not analyze the lacunar stroke subgroup. Mortality cases were sparse; the resulting regression
Conclusion
In patients with ischemic stroke, initial hyperlactatemia represents an independent risk factor for poor outcome at 3 months, after controlling for stroke severity, risk factors, and interval from onset of stroke symptoms to ED arrival. Hyperlactatemia showed a trend of death at 3 months.
Acknowledgment
We offer special thanks to Yujin Jo for assistance with data collection.
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