Brain natriuretic peptide: an early marker of ICU mortality.

Study Question: What is the value of BNP as a predictor of death and risk of cardiovascular events in patients admitted to the ICU? BNP levels were assessed in 15 sequential patients admitted to ICU unresponsive, intubated and hypotensive. BNP levels at presentation were associated with an increase risk of death and risk of myocardial infarction even in patients who had negative initial Troponin 1 (<0.1 ng/ml) at baseline (P < 0.001). In patients with subsequent elevation of Troponin I, the baseline BNP levels independently predict risk of atrial fibrillation during hospital course (P < 0.001). A single initial measurement of BNP independently predicts the early risk of ICU mortality. Furthermore BNP level provides information on risk myocardial infarction and increased risk of atrial fibrillation in patients admitted to ICU without detectable myocardial necrosis marker on admission (Troponin I, and Creatinine kinase MB isoforms). Perspective: BNP is a cardiac neurohormone that is synthesized in ventricular myocardium and released in response to increased ventricular wall stress. Ischemia and hypoxia are important stimulus for BNP release. The present study demonstrates elevated BNP level commonly observed in patients admitted to the ICU due to increased cardiac demand and increased ventricular wall stress. Elevated BNP level serves as a predictor of ICU mortality, risk of myocardial infarction and atrial fibrillation during hospital course. However these impressive findings of the usefulness of single BNP levels on admission to ICU need to be confirmed in prospective studies involving large number of patients.

Anil K. Goli, MD, Sujatha A. Goli, MD, Madhav Koduri, MD, Ryland P. Byrd, Jr, MD, Thomas M. Roy, MD, and Stephen A. Fahrig MD. Department of Internal Medicine, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN.