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Admission N-terminal pro-brain natriuretic peptide and its interaction with admission troponin T and ST segment resolution for early risk stratification in ST elevation myocardial infarction
  1. E Björklund1,
  2. T Jernberg3,
  3. P Johanson3,
  4. P Venge4,
  5. M Dellborg3,
  6. L Wallentin4,
  7. B Lindahl2,
  8. the ASSENT-2 and ASSENT-PLUS Study Groups
  1. 1Department of Cardiology, University Hospital of Uppsala, Uppsala, Sweden
  2. 2Uppsala Clinical Research Centre, University Hospital of Uppsala, Uppsala, Sweden
  3. 3Clinical Experimental Research Laboratory, Sahlgrenska University Hospital/Östra, Göteborg, Sweden
  4. 4Department of Clinical Chemistry, University Hospital of Uppsala, Uppsala, Sweden
  1. Correspondence to:
    Dr Erik Björklund
    Department of Cardiology, University Hospital, 751 85 Uppsala, Sweden; erik.bjorklund{at}akademiska.se

Abstract

Objective: To assess the long term prognostic value of N-terminal pro-brain natriuretic peptide (NT-proBNP) on admission and its prognostic interaction with both admission troponin T (TnT) concentrations and resolution of ST segment elevation in fibrinolytic treated ST elevation myocardial infarction (STEMI).

Design and setting: Substudy of the ASSENT (assessment of the safety and efficacy of a new thrombolytic) -2 and ASSENT-PLUS trials.

Patients: NT-proBNP and TnT concentrations were determined on admission in 782 patients. According to NT-proBNP concentrations, patients were divided into three groups: normal concentration (for patients ⩽ 65 years, ⩽ 184 ng/l and ⩽ 268 ng/l and for those > 65 years, ⩽ 269 ng/l and ⩽ 391 ng/l in men and women, respectively); higher than normal but less than the median concentration (742 ng/l); and above the median concentration. For TnT, a cut off of 0.1 μg/l was used. Of the 782 patients, 456 had ST segment resolution (< 50% or ⩾ 50%) at 60 minutes calculated from ST monitoring.

Main outcome measures: All cause one year mortality.

Results: One year mortality increased stepwise according to increasing concentrations of NT-proBNP (3.4%, 6.5%, and 23.5%, respectively, p < 0.001). In receiver operating characteristic analysis, NT-proBNP strongly trended to be associated more with mortality than TnT and time to 50% ST resolution (area under the curve 0.81, 95% confidence interval (CI) 0.72 to 0.9, 0.67, 95% CI 0.56 to 0.79, and 0.66, 95% CI 0.56 to 0.77, respectively). In a multivariable analysis adjusted for baseline risk factors and TnT, both raised NT-proBNP and ST resolution < 50% were independently associated with higher one year mortality, whereas raised TnT contributed independently only before information on ST resolution was added to the model.

Conclusion: Admission NT-proBNP is a strong independent predictor of mortality and gives, together with 50% ST resolution at 60 minutes, important prognostic information even after adjustment for TnT and baseline characteristics in STEMI.

  • ASSENT, assessment of the safety and efficacy of a new thrombolytic
  • AUC, area under the curve
  • BNP, brain natriuretic peptide
  • CASS, coronary artery surgery study
  • CI, confidence interval
  • MI, myocardial infarction
  • NT-proBNP, N-terminal pro-brain natriuretic peptide
  • OR, odds ratio
  • ROC, receiver operating characteristic
  • STEMI, ST elevation myocardial infarction
  • TnT, troponin T
  • acute myocardial infarction
  • brain natriuretic peptide
  • prognosis
  • electrocardiography

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Footnotes

  • Published Online First 26 October 2005

  • Competing interests: None declared.

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