Cardiac Biomarkers -Myocardial Infarction (MI)

Myocardial infarction (MI), biomarkers of myocardial infarction (MI), definition of biomarker, troponin I and troponin T, myoglobin, CK-MB, Creatine kinase (CK), best biomarker of myocardial infarction (MI), Laboratory investigations of myocardial infarction (MI), sepecific biomarker of, MI, sensitive, biomarker of MI, Normal range of biomarkers of MI, Elevation of biomarkers of myocardial infarction (MI) with time, Graph showing time course elevation of CK-MB, Myoglobin and Cardiac troponins, prabin kumar bam, chitwan medical college, bharatpur, nepal

1. Prabin Kumar Bam MBBS,Chitwan Medical College Nepal

2. Learning reflections To know the definition of biomarkers. To understand the biomarkers of myocardial infarction.

3. BIOMARKERS OF MYOCARDIAL INFARCTION

4. Biomarker is any molecule, enzyme, hormone or gene which is measured and evaluated as an indicator of normal biological process or to identify the presence of any disease of body. For example; body tempt. is a well known biomarker for fever, cholesterols are biomarkers for cardiovascular diseases. An ideal biomarker must be specific, sensitive, prognostic, longer persisting, reliable, quick & inexpensive.

5. BIOMARKERS FOR MI Cardiac proteins Troponin I and Troponin T Myoglobin Cardiac enzymes CK-MB

6. RANGE AND ELEVATION OF BIOMARKERS WITH TIME MARKER NORMAL VALUES ONSET PEAK RETURN TO NORMAL CK-MB 5-25IU/L 3-6 hrs. 18-24 hrs 36-72 hrs. Myoglobin 0-85ng/ml 1-4 hrs. 6-7 hrs. 24 hrs. Troponin I 4 hrs. 14-24 hrs. 5-10 days Troponin T <0.01 ng /ml 6 hrs. 72 hrs. 10-14 days

7. Time course of elevation of ck-mb & troponins in blood of mi patient

8. Troponin I & T Troponin is a muscle protein which helps in contraction. It consists of 3 subunits: Troponin I (affinity for actin) Troponin C (Calcium binding) Troponin T ( Tropomyosin binding)

9. Troponin I & T are most sensitive and specific biomarkers of MI at any interval after the heart attack. Troponins are specific for MI because they are not increased in muscle injury where as CK-MB is slightly raised in some muscle injuries.

10. CREATINE KINASE / CK It catalyzes the following reaction: Creatine phosphate ----- ---- Creatine It has 3 iso -enzymes: Iso -enzyme Tissue of origin % in blood CK-MM Skeletal muscle 80% CK-MB Heart 5% CK-BB Brain 1%

11. Earlier, total serum CK was employed as a biomarker of MI. But, nowadays only CK-MB level is measured. It is because total serum CK level is very much elevated in diseases like muscular dystrophy, fracture & cerebrovascular accidents . So, it becomes quite unspecific for determining MI.

12. CK-MB It is less specific than troponin I & T since it is slightly elevated in skeletal muscle injury also. It is useful for early diagnosis and diagnosis for re-infarction. However, it cannot be used in the case of delayed admission (more than 2 days).

13. MYOGLOBIN It is a protein found in muscles and helps in transportation of oxygen. It appears in blood earlier than other markers i e; it has high sensitivity so it can be used for early diagnosis. Since myoglobin is found in all 3 types of muscles (skeletal, cardiac & smooth) and in renal tissues it is not a specific biomarker for MI.

14. RECOMMENDATIONS FOR USE OF BIOMARKERS OF MI Recommended for all patients complaining of chest pain (with ECG & clinical examinations ). Sample: Plasma Sequence: Early marker- Myoglobin (appears in blood early), but non-specific & doesn’t persists for long time.

15. Definitive marker: Troponin (appears in blood latter than Mb ) and is 100% specific and stays longer. It is the first choice.

16. REFERENCES Harper,s illustrated biochemistry Lippincott’s biochemistry Textbook of biochemistry by DM Vasudevan Biochemistry by U. Satyanarayana

17. Thank you