Cardiac markers

Diagnosis of MI

The most serious type of ischemic injury is acute myocardial infarction (AMI). Transient and fully reversible myocardial ischemia is called angina pectoris . Clinical manifestations:

Classical tests in the diagnosis of MI

Test enzyme Standard The beginning of the rise Maximum Standardization Multipler at maximum
Aspartate aminotransferase (AST) < 0,67 μkat/l 4–8 h 16–48 h 3–6 days Up to 25
Creatine kinase (CK) men < 3,2 μkat/l 3–6 h 16–36 h 3–5 days Up to 25
women < 2,4 μkat/l
CK-MB isoenzyme < 0,4 μkat/l, < 6 % of total CK activity
Lactate dehydrogenase(LD) < 8 μkat/l 6–12 h 24–60 h 7–15 days Up to 8
LD isoenzymes

New tests in the diagnosis of MI

Myoglobin, CK MB mass and Troponin, their serum levels during myocardial ischemia
Myoglobin
  • cytoplasmic protein, source of O2 in the anaerobic phase of contraction
  • in the blood 0.5-2 h after MI (sensitivity 4-5 h)
  • small molecule (Mr = 17,100), rapidly lost from the blood through the glomeruli
  • standard
  • M < 92 µg/l
  • F < 76 µg/l
CK-MB mass isoenzyme (antigen determination)
  • concentration is given in mass units (µg/l) !!
  • degraded molecules also react to the antigen (higher sensitivity)
  • standard: < 5 µg/l
Test enzyme The beginning of the rise Maximum Standardization Multiplier at maximum
Myoglobin 0,5–2 h 6–12 h 0,5–1 d Up to 20
Troponin T 3,5–10 h 12–18 h (3–4 d) 7–20 d Up to 300
First recruitment on admission - STATIM
  • Basic parameters for broader differential diagnosis: Na, K, Cl, urea, creatinine, Ca, uric acid, cholesterol, TAG, total bilirubin, ALT, AST, ALP, GMT, LD, CRP
  • Cardiac markers:
  • CK, CK-MB
  • Myoglobin – difficulties lasting 2-12 hours, normal renal function
  • Troponin T:
  • a) within 8 hours to exclude AMI
  • b) after 12 hours to diagnose microinfarcts
Further recruitment
  • 2. Recruitment in 6 ± 2 hours (CK, CK-MB, troponin T, Myoglobin)
  • 3. Recruitment in 12 ± 2 hours (CK, CK-MB if the diagnosis or extent of involvement is not clear)
  • 4. Recruitment in 24 ± 2 hours - exceptionally

Interpretation of results

Myoglobin

  • < 30 µg/l
  • normal in healthy, excludes AMI between 6 and 10 hour
  • 30–70 µg/l
  • if the concentration rises to less than 40 µg/l within 1 h, MI can be ruled out
  • > 70 µg/l
  • excluding skeletal muscle damage, MI

Troponin T

  • < 0.05 µg/l - MI can be excluded, repeat in 10-12 h
  • 0.05-0.1 µg/l - it is recommended to repeat testing in 1 hour
  • 0.1-3 µg/l - myocardial damage
  • > 3 µg/l - massive myocardial damage

Troponin I

  • <0.1 µg/l - MI can be excluded
  • 0.6-1.5 µg/l - according to the WHO this is evidence of MI
Confirmation of myocardial reperfusion
Analyze Myocardial reperfusin
Successful Unsuccessful
C1–C0 (µg/l) Tmax–T0(h) Tmax–T0(h)
Myoglobin > 150 < 3 > 12
CK MBmass > 10 < 8–12 > 12
Troponin T > 0,2 < 14 > 14
Troponin I > 100 < 14 > 14

Natriuretic peptides

Structure of BNP
  • Hormones synthesized in atrial and ventricular cardiomyocytes
  • Maintain electrolyte and volume homeostasis
  • ANP, BNP - produced by cardiomyocytes
  • CNP - produced by vascular endothelial cells and renal epithelium


Resource