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18-08-2011 | Cardiology | Article

NT-proBNP ‘significantly improves’ diagnosis of suspected AMI

Abstract

Free abstract

MedWire News: N-terminal pro-B type natriuretic peptide (NT-proBNP) significantly improves the early diagnosis and risk-stratification of patients with suspected acute myocardial infarction (AMI), a study suggests.

Experimental and clinical studies have demonstrated that myocardial ischemia is a strong trigger of NT-proBNP release, explain Philip Haaf (University Hospital, Basel, Switzerland) and co-authors in the American Journal of Medicine. They therefore decided to investigate whether NT-proBNP could be used in the diagnosis of AMI.

The prospective multicenter study included 658 consecutive patients with acute chest pain who were followed-up for 24 months for the primary outcome of mortality. The authors measured NT-proBNP levels in all patients at presentation, and two independent cardiologists adjudicated a diagnosis of AMI at 60-day follow-up.

AMI was diagnosed in 117 (18%) patients. Patients who were diagnosed with AMI had higher NT-proBNP levels at presentation (median 886 pg/ml than those with other diagnoses, including unstable angina (median 259 pg/ml) and patients without an acute coronary syndrome (median 111 pg/ml; p<0.001 for all comparisons).

Analysis of the area under the receiver operating characteristic curve (AUC) demonstrated that the diagnostic accuracy of NT-proBNP for AMI was 0.79. When added to cardiac troponin T, NT-proBNP significantly increased the AUC from 0.89 to 0.91 (p=0.033).

The cumulative 24-month mortality rates were 0%, 1.3%, 8.3%, and 23.3% in the first, second, third, and fourth quartiles of NT-proBNP, respectively (p<0.001), the authors report.

NT-proBNP predicted all-cause mortality independently and more accurately than both troponin T and the Thrombolysis in Myocardial Infarction (TIMI) Risk Score, with AUCs of 0.85, 0.66, and 0.79, respectively (all p<0.001).

In a comparison of TIMI Risk Score alone versus TIMI Risk Score and NT-proBNP, the net reclassification improvement was 0.188 (p<0.009) and integrated discrimination improvement was 0.100 (p<0.001).

"Using a dual-marker strategy, measuring cTn and NT-proBNP improves both the early diagnosis and risk-stratification of patients with suspected AMI," conclude the authors.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Piriya Mahendra

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