N-Terminal B-Type Natriuretic Peptide Assessment Provides Incremental Prognostic Information in Patients With Acute Coronary Syndromes and Normal Troponin T Values Upon Admission

Abstract

Objectives: The purpose of this study was to determine the prognostic value of N-terminal B-type natriuretic peptide (NT-proBNP) in two independent samples of patients presenting with acute coronary syndromes (ACS) and normal troponin T (TnT) values. Background: Recently assessment of NT-proBNP has been studied in patients with ACS. However, the clinical relevance in patients who present without troponin elevation is unclear. Methods: We included 2,614 patients from two independent registries, one serving as a derivation cohort comprising patients with evident ACS (Bad Nauheim ACS registry, n = 1,131) and the other serving as a validation cohort including chest pain patients (PACS [Prognosis in Acute Coronary Syndromes] registry, n = 1,483). NT-proBNP and TnT were measured upon admission. Clinical outcome has been assessed over a 6-month period. Results: In both cohorts, the mortality rate was significantly lower among TnT negative patients: 3.8% versus 8.2% (p = 0.009) in the Bad Nauheim ACS registry, and 2.8% versus 8.6% (p = 0.009) in the PACS registry. Among TnT negative patients, receiver-operating characteristics curve analysis yielded an optimal cutoff value of 474 pg/ml for NT-proBNP that was able to discriminate patients at higher risk in the Bad Nauheim ACS and PACS registries (mortality rate 12.3% vs. 1.3%, p < 0.001 and 8.5% vs. 1.5%, p < 0.001, respectively). By Kaplan-Meier analysis, patients with NT-proBNP values over 474 pg/ml were at higher risk for death in the Bad Nauheim ACS registry (log-rank 19.01, p < 0.001, adjusted hazard ratio [HR] 9.56 [95% confidence interval (CI) 2.42 to 37.7], p = 0.001) and in the PACS registry (log-rank 23.16, p < 0.001, adjusted HR 5.02 [95% CI 2.04 to 12.33], p < 0.001). Conclusions: Among patients with suspected ACS considered to be at low risk because of normal troponin values, NT-proBNP above 474 pg/ml is able to discriminate individuals at higher risk. Because of its incremental prognostic value, NT-proBNP assessment should be considered in clinical routine for risk stratification of patients with normal troponin. © 2008 American College of Cardiology Foundation.