Btype Natriuretic Peptide BNP in the Diagnosis of Acute Congestive Heart Failure CHF

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B-type Natriuretic Peptide(BNP) in the Diagnosis
of Acute Congestive Heart Failure (CHF)

• Scott M Silvers MD
• 1st Annual Pan American Conference
• Emergency Medicine Clinical Policies
• November 6 7 2003

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Lecture Outline

• Introduction to BNP
• Case
• Critical Question
• Literature Search
• Critical Literature Evaluation
• Evidence-based Recommendations

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Introduction to BNP

• 32-aa polypeptide
• Found in heart ventricles
• Produced with ventricular stretch and volume
• Results in vasodilation natriuresis diuresis
  and reduced preload
• Increases with worsening heart failure

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Introduction to BNP
Maisel AS et al. N Engl J Med.
2002347(3)161-167.
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Introduction to BNP
Morrison LK et al. J American Coll of Card.
200239(2)202-209.
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Case

• Current History
• Ms. GM is a 76 yo woman with a history only of
  obstructive lung disease who presents to the
  emergency department with 2 days of progressively
  worsening shortness of breath.
• Physical Examination
• T 37C HR 110 BP 170/90 RR 40 SO2
  (air) 87
• She is unable to speak long sentences.
• Neck veins difficult to assess
• Heart difficult to hear over her lung sounds
• Lungs diffuse wheezing with decreased breath
  sounds and rales at the bases
• Abdomen normal
• Extremities warm with moderate pitting edema

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Chest X-ray
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Critical Question

• What is the utility of a B-type natriuretic
  peptide (BNP) measurement in the diagnosis of
  congestive heart failure among patients
  presenting to an emergency department
  with shortness of breath

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Curiosity Poll

• How many people have a BNP assay available to
  them where they practice

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Literature Search

• Medline January 1995 Present
• Keywords
• Brain natriuretic peptide B-type natriuretic
  peptide B natriuretic peptide or BNP
• 1 745 papers
• Limits
• Human subjects clinical trials meta-analyses
• 164 papers

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Literature Search

• Abstracts of clinical studies reviewed
• Patients presenting with shortness of breath to
  acute care centers
• 5 papers
• Reviews and clinical policies 2000 - present
  (references crosschecked)

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Typical Study Methodology

• Inclusion Criteria

• Adult patients presenting to an acute care
  facility
• Primary complaint shortness of breath

Exclusion Criteria

• Obvious non-CHF cause of shortness of breath
• Renal Failure
• Acute myocardial infarction

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Typical Study Methodology

• Evaluation by an emergency physician
• Assessment of clinical probability of CHF
• BNP assay sent
• Results not revealed to emergency physician
• Patient treated and dispositioned
• Physician team blinded to BNP measurement assign
  final diagnosis after evaluation of case

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Typical Study Methodology

• CHF Gold Standard

• Clinical findings
• Chest x-ray
• Echocardiography
• Nuclear cardiology
• Cardiac Catheterization
• Framingham and NHANES scores
• Clinical response to therapies

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Critical Literature EvaluationBNP in Diagnosing
CHF

• 5 published studies to date
• 2 report data from the same sample

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Critical Literature EvaluationBNP in Diagnosing
CHF
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Critical Literature EvaluationBNP in Diagnosing
CHF

• Maisel et al (NEJM 2002)

• Prospective multinational N 1586
• All clinical risk patients evaluated as one
  sample
• BNP
• Sensitivity 90 Specificity 76
• NPV 89 PPV 79
• BNP
• Sensitivity 97 Specificity 62
• NPV 96 PPV 71
• Study Grade 1

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Critical Literature EvaluationBNP in Diagnosing
CHF

• McCullough et al (Circulation 2002)

• Prospective multinational N 1538
• Excluded 48 patients without clinical risk
  assessement
• BNP
• Low and Intermediate clinical probability (0
  79)
• Sensitivity 94 Specificity 70
• NPV 93 PPV 74
• High clinical probability (80 100)
• Sensitivity 49 Specificity 96
• NPV 68 PPV 91
• Study Grade 2 (Post-study Analysis)

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Critical Literature Evaluation
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Critical Literature Evaluation
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Critical Literature Evaluation
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Critical Literature Evaluation
Maisel AS et al. N Engl J Med.
2002347(3)161-167.
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Critical Literature Evaluation

• Possible Limitation of BNP
• Among rats given acute CHF BNP may take over 1
  hour to rise.

Nakagawa O et al. J Clin Invest.
1995961280-1287.
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Evidenced-based Recommendations

• Includes

• Patients presenting to an emergency department
• Primary complaint shortness of breath

Excludes

• Obvious non-CHF cause of shortness of breath
• Renal Failure
• Acute myocardial infarction

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Evidenced-based Recommendations

• Level A Recommendations

• A BNP rule-out the diagnosis of congestive heart
  failure when the diagnosis is uncertain.
  (Probability

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Evidenced-based Recommendations

• Level B Recommedations

• Among low and intermediate clinical probability
  patients a BNP used to help rule-out the diagnosis of congestive
  heart failure. (Probability
• Among patients without a history of CHF a BNP
  88 pmol/L (400 pg/ml) may be used to rule-in the
  diagnosis of CHF when the diagnosis is uncertain.
  (Probability 95)
• A BNP 220 pmol/L (1000 pg/ml) may be used to
  rule-in the diagnosis of acute CHF among patients
  presenting with a history of CHF. (Probability
  95)

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Evidenced-based Recommendations

• Level C Recommendations

• When evaluating a patient who presents with
  possible CHF within 1 hour from symptom onset
  use caution in the interpretation of a low BNP
  level as BNP may take over 1 hour to rise.

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Key References

• Davis M et al. Plasma brain natriuretic peptide
  in assessment of acute dyspnea. Lancet.
  1994343440-444.
• Dao Q et al. Utility of B-type natriuretic
  peptide in the diagnosis of congestive heart
  failure in an urgent-care setting. J Amer Coll
  Card. 200137(2)379-385.
• Morrison LK et al. Utility of a rapid
  B-natriuretic peptide assay in differentiating
  congestive heart failure from lung disease in
  patients presenting with dyspnea. J Amer Coll
  Card. 200239(2)202-209.
• Maisel AS et al. Rapid measurement of B-type
  natriuretic peptide in the emergency diagnosis of
  heart failure. New Eng J Med.
  2002347(3)161-167.
• McCullough PA et al. B-typenatriuretic peptide
  and clinical judgement in emergency diagnosis of
  heart failure Analysis from breathing not
  properly (BNP) multinational study. Circulation.
  2002106416-422.
• Nakagawa O et al. Rapid transcriptional
  activation and early mRNA turnover of brain
  natriuretic peptide in cardiocyte hypertrophy. J
  Clin Invest. 1995961280-1287.

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The End