Cardiac Biomarkers

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Cardiac Biomarkers

• Tiffany Boyd BSN, RN, PCCN
• Staff Development Instructor
• Sarah Harne-Britner MSN, RN, CCRN
• Cardiac Clinical Nurse Specialist

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Cardiac MarkersA piece of the puzzle

• Represent leakage of cell contents from myocytes
  which are released when damage to the tissue
  takes place
• Elevated levels indicate myocardial damage, but
  do not determine cause
• Used in conjunction with history, signs/symptoms,
  exam and ECG changes to make diagnosis

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Perfect Cardiac Marker

• Early appearance
• Accurate, specific, precise
• Readily available, fast results
• Cost-effective

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Markers for Cardiac Injury

• Creatine Kinase (CK-MB)
• Relative Index (RI)
• Troponins T I
• Myoglobin

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Creatine Kinase

• Found in heart, skeletal muscle, brain
• CK-MB is the isoform found primarily in cardiac
  muscle
• Normal values
• CK 21-240 u/L
• MB 0-5 ng/ml
• RI 0-4
• Timing
• Earliest Rise 4-8 hrs
• Peak 12-24 hrs
• Return to normal 3-4 days

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Creatine Kinase-MB

• PROS
• 90 accuracy for detecting myocardial necrosis
  within 4-6 hours after onset
• Readily available
• Good for detecting re-infarction

• CONS
• Levels dont start to rise for 4 hrs after onset
• Other conditions can cause elevations

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Elevated CK-MB

• Elevation 5-10 times the normal in post CABG
  patients associated with increased mortality at
  30 days, 6 months, and 1, 3, 5 years.
• Elevation in post intervention patients without
  MI is associated with increased mortality at 1
  year.

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Relative Index (RI)

• Comparison of CPK to CPK-MB
• gt4.0 can be indicative of MI

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Troponin

• Protein found in skeletal and contractural fibers
  of the heart (cardiac muscle)
• Troponin I and T are cardiac specific
• Normal 0-0.3 ng/ml
• Timing
• Earliest rise 3-4 hrs
• Peak 10-24 hrs
• Return to Normal 1-3 wks

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Troponin

• PROS
• Troponin T and I can detect MI, ACS and PE
• Troponin T and I more sensitive than CK-MB
• Allows earlier and longer window to identify MI
  and ACS

• CONS
• False positives can occur with rheumatoid
  arthritis and renal failure patients
• Not good to detect reinfarction

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Elevated Troponin

• Patients with elevated Troponin I levels, normal
  CK-MB and no ST elevation have an increased risk
  of death
• Varied results in mortality for post intervention
  patients with elevated Troponin I
• Useful marker for post-op cardiac surgery patient

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Myoglobin

• Protein found in cardiac and skeletal muscle
  assists in oxygen transport
• Released from damaged tissue within 1 hour
• Normal value 17.4-105.7 ng/ml
• Timing
• Earliest Rise 1-3 hrs
• Peak 6-9 hrs
• Return to normal 12 hrs

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Myoglobin

• PROS
• Provides earliest detection of AMI
• Best marker to exclude AMI if patient presents
  within 4 hrs of symptom onset
• Useful to detect reinfarction

• CONS
• Elevations not specific to cardiac muscle injury
• Concentration elevated in patients with renal
  insufficiency

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C-Reactive Protein (CRP)

• Non-specific marker for inflammation, tissue
  damage and infection
• Previously used for rheumatoid arthritis,
  inflammatory bowel disease, arteritis and lupus
• Marker for screening and prevention of CAD
• Useful to determine prognosis for recurrent
  events (death, MI, restenosis after PCI)
• Results lt1.0 mg/L low risk
• 1.0 to 3.0 mg/L average risk
• gt 3.0 mg/L high risk

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B Type Natriuretic Peptide (BNP)

• Hormones released in response to volume expansion
  and increased intracardiac pressure
• BNP is found in the myocardium and released by
  the ventricles
• Tool in the diagnosis and management of heart
  failure
• Normal value 1-100 pg/ml

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Serum Enzymes
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Our Case Study

• Time 1615 2110 0445 1440
• Lab
• CK 332 1872 1507 840
• CKMB 8.0 221.9 209.0 105.3
• RI 2.4 11.9 13.9
  12.5
• Trop 0.09(bedside) 61.13 50.79 24.24