B-type natriuretic peptide as a marker for sepsis-induced myocardial depression in intensive care patients

In early stages of septic shock, impaired myocardial function plays an important prognostic role. In this context, B-type natriuretic peptide (BNP) has been shown to be a neurohumoral marker for left ventricular dysfunction, because myocardial strain and ischemia both increase BNP concentration. The present study was designed to test if BNP allows for identification of patients at risk for developing sepsis-induced myocardial depression and if an increased concentration of BNP is associated with an adverse outcome in patients with septic shock.

In a prospective study, 93 patients with septic shock were divided into one group with normal ventricular function (left ventricular ejection fraction >50%) on days 3 to 5 (n = 38) and another group of patients with impaired left ventricular function (left ventricular ejection fraction <50%) on days 3 to 5 (n = 55). Patients with impaired left ventricular function had an increased median plasma BNP concentration on day 5 (699 [608 of 795.5] pg/nL vs. 86 [71.3 of 93] pg/nL) and an ejection fraction of 38 +/- 6% on day 5 vs. 58 +/- 7% in patients without impaired left ventricular function. There was a close inverse relation between increased plasma BNP concentrations and depressed left ventricular ejection fraction (p < 0.05). BNP measured at days 3 and 5 revealed an association with the end point of survival. In the proportional hazards regression model adjusted for age, male gender, and creatinine concentration, measured at days 0, 3, 5, and 12, BNP concentration at day 5 showed an increased hazard for reaching the end point (hazard ratio: 1.407; 95% confidence interval: 1.033-1.916; p = 0.030). In an additional receiver operating characteristic curve analysis, the predictive value of a model including cardiovascular risk factors and additional BNP concentration on day 5, compared with a baseline model of cardiovascular risk factors, improved the area under the curve the most; therefore, this model was suited best for prediction of sepsis-induced myocardial depression and 30-day survival for patients with septic shock. Area under the curve of this model combined with BNP concentration at day 5 for death after 30 days (0.65) impaired left ventricular ejection fraction (0.94) and sepsis-induced myocardial depression (0.96).

These results indicate that plasma BNP concentration represents a reliable marker for identification of patients developing sepsis-induced myocardial depression. In addition, BNP concentration on day 5 may be used as a prognostic marker to identify patients with an elevated risk for an adverse outcome.