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:
 * Pain in the chest
 * Changes on ECG
 * Changes in biochemical markers

New tests in the diagnosis of MI



 * 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

Recommended procedure for biochemical examination in suspected AMI

 * 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

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

Natriuretic peptides

 * 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

Related articles

 * Cardiac markers in AMI