[Brain natriuretic peptide in acute coronary syndromes: utility of NT-pro BNP assay]

Abstract

Better risk stratification strategies are required for patients with acute coronary syndromes. Plasma myocardial troponin is a specific but poorly sensitive marker. Levels of B natriuretic peptide, a 32-amino-acid peptide synthesized and released by left ventricular myocytes, correlate strongly both with the presence of acute myocardial lesions and with vital outcome. To address the possible influence of the sampling time, we measured NT-pro BNP plasma concentrations on emergency admission and 8 and 24 hours later in 64 patients with acute coronary syndromes. Troponin levels were abnormal in respectively 44%, 51% and 52% of patients, while NT-pro BNP levels were abnormal in 75%, 83% and 79% of patients (p < 10(-4)). Both troponin and NT-pro BNP levels were abnormal in patients with ST elevation MI (n = 15; 93% and 87%, NS) and in patients with non ST elevation MI (n = 19; 73% and 68%). In contrast, among 30 patients with unstable angina, troponin levels were always normal whereas NT-pro BNP levels were elevated in 73% of cases (p < 10(-4)). This suggests that more than 50% patients with acute coronary syndromes who have normal troponin levels 8 hours after admission--and would therefore be discharged--would qualify for further investigations on the basis of natriuretic peptide levels. NT-pro BNP is thus more sensitive than troponin as a marker of myocardial damage. In addition, its clinical significance is not influenced by the precise sampling time within 24 hours following emergency admission. NT-pro BNP therefore adds important information for patient stratification.