Abstract 88: High NT-proBNP in Cardiopulmonary Resuscitated Patients Treated With Mild Therapeutic Hypothermia is Associated With Mortality

Abstract

Introduction: Despite the apparent appropriateness of mild therapeutic hypothermia (MTH) to limit neurological injury and improve survival in patients with return of spontaneous circulation (ROSC) after cardiac arrest (CA), mortality rates remain high. To date, no accurate and independent biomarker to predict survival in these patients exists. B-type natriuretic peptide (BNP) was found to provide both prognostic and diagnostic value in various cardiovascular diseases. However, the biologically inactive counterpart of BNP, NT-proBNP, was found to be more stable and accurate. Objective: Investigate the value of NT-proBNP to predict 28-day mortality in post-CA patients treated with MTH, as well as the influence of MTH on NT-proBNP levels. Methods and Results: NT-proBNP levels were measured in post-CA patients who were non-invasively cooled using body wraps (Medi-Therm ® , Gaymar). Plasma samples were obtained before cooling was started, during 24 hours maintenance and at the end of re-warming. Between 2009 and 2013 327 patients were admitted to the ICU for post-CA MTH treatment. Baseline NT-proBNP values were available for 81 (25%) patients and were subsequently included for the evaluation of NT-proBNP as a prognostic marker. In the 28 days following ICU admission, 38 patients died (47%). Non-survivors had significantly higher baseline NT-proBNP levels (median 1525ng/l, IQR 450-3859 versus median 267ng/l, IQR 99-1766; P <0.001) compared to survivors. Adjusted odds ratios for 28-day mortality were 3.3 (95% CI = 0.8, 13.4), 4.4 (95% CI = 1.1, 17.8) and 9.3 (95% CI = 2.2, 40) for increasing quartiles of NT-proBNP as compared to the lowest quartile. A cut-off value of 643ng/l achieved a sensitivity of 67% and a specificity of 66% to predict 28-day mortality. During the different phases of MTH NT-proBNP values decreased or increased. The presence of either pattern in NT-proBNP expression was not associated with outcome. Conclusions: High NT-proBNP plasma levels on ICU admission are associated with high mortality in post-CA patients, but are of moderate prognostic value as an independent biomarker. Increases or decreases in patterns of NT-proBNP expression during the separate phases of MTH treatment appear unrelated to 28-day mortality.