N-terminal pro B-type natriuretic peptide in the early evaluation of suspected acute myocardial infarction

BACKGROUND: Myocardial ischemia is a strong trigger of N-terminal pro-B-type natriuretic peptide (NT-proBNP) release. As ischemia precedes necrosis in acute myocardial infarction, we hypothesized that NT-proBNP might be useful in the early diagnosis and risk stratification of patients with suspected acute myocardial infarction.

METHODS: In a prospective multicenter study, NT-proBNP was measured at presentation in 658 consecutive patients with acute chest pain. The final diagnosis was adjudicated by 2 independent cardiologists. Patients were followed long term regarding mortality.

RESULTS: Acute myocardial infarction was the adjudicated final diagnosis in 117 patients (18%). NT-proBNP levels at presentation were significantly higher in acute myocardial infarction as compared with patients with other final diagnoses (median 886 pg/mL vs 135 pg/mL, P <.001). The diagnostic accuracy of NT-proBNP for acute myocardial infarction as quantified by the area under the receiver operating characteristic curve (AUC) was 0.79 (95% confidence interval [CI], 0.75-0.83). When added to cardiac troponin T, NT-proBNP significantly increased the AUC from 0.89 (95% CI, 0.84-0.93) to 0.91 (95% CI, 0.88-0.94; P=.033). Cumulative 24-month mortality rates were 0% in the first, 1.3% in the second, 8.3% in the third, and 23.3% in the fourth quartile of NT-proBNP (P <.001). NT-proBNP (AUC 0.85, 95% CI, 0.81-0.89) predicted all-cause mortality independently of and more accurately than both cardiac troponin T (AUC 0.66, 95% CI, 0.58-0.74; P <.001) and the Thrombolysis in Myocardial Infarction risk score (AUC 0.79, 95% CI, 0.74-0.84; P <.001). Net reclassification improvement (Thrombolysis in Myocardial Infarction vs additionally NT-proBNP) was 0.188 (P <.009), and integrated discrimination improvement was 0.100 (P <.001).

CONCLUSIONS: Use of NT-proBNP improves the early diagnosis and risk stratification of patients with suspected acute myocardial infarction.