1. Cardiac enzymes. 2 – Non enzyme proteins The Troponins
Dr Muhammad Ramzan

2. Cardiac Troponin – the definition A muscle protein
Cardiac Troponins are the regulatory proteins that control the Calcium mediated interactions B/W Actin and Myosin
Cardiac Troponin consists of 2 subunits and include Troponin I (cTnI) and Troponin T (cTnT))
– Webster.com – J Clin Pathol.2004

3. Cardiac Troponins (cTn) – the background non enzyme proteins
Troponin is a muscle protein of 3 subunits (cTnI, cTnT and TnC) and a part of native Tropomycin
Cardiac Troponin are low/absent in smooth muscles
Have different Amino acid sequence for their detection through Monoclonal antibody assay
Troponins are released into the plasma in response to cardiac (MI) and skeletal muscle damage
Alpert et al,2000 –

4. Cardiac Troponins – the properties bound and free floating
cTn are coded by specific genes and are :
Unique to Cardiac muscles
Have shorter half life of 90 minutes
appear 3-4 hours after symptoms
Alpert et al,2000 (Tunstall- Paedo et al. 1994) –

5. Cardiac Troponin – the properties cont.
Majority of the cTn are bound to myofilaments but remainder is free floating in the cytoplasm
This is in comparison to the CKMB which is fully Cytosolic
cTn levels are normally too low to be detected in plasma or
have no base line
Alpert et al,2000 (Tunstall- Paedo et al. 1994) –

6. cTn – Cytosolic and filamentous 2 peaks

7. Release of cTn – the mechanism injury to the cardiac Cell membrane
Cardiac injury occurs when membrane of normal cardiac myocyte is damaged ( Ischaemia /MI)
It results in the loss of Troponin; intracellular/ structural proteins like Troponins; Enzymes, blood and :
Myoglobin into Extra cellular space – cardiac biomarkers
The subsequent release is maintained by the degradation of the Actin and Myosin filaments

8. Release of cTn – the mechanism

9. Cardiac Troponin – 2 Types
There are 2 types of Troponins, present in cardiac muscles with certain differences
These are:
Cardiac Troponin T - cTnT
Cardiac Troponin I - cTnI

10. Cardiac Troponin – Pattern of rise and fall 2 Peaks and clearance
cTn has 2 peaks – an early/Cytosolic and late/muscular
Cytosolic pool is released first in the blood hrs
Late peak is achieved in 24 hrs by muscle degradation
cTn is cleared lately ( 2 wks), opposite to the CKMB which gets cleared in 3- 4 days
cTn I value of >20ng/ml is diagnostic of 90% cases of MI
Neumayr et al, –

11. Elevation of Troponins in MI >20ng/ml – 90% MI

12. Causes of elevated cTn These are divided into 2
1. Cardiac /CAD causes – the commonest and major ones include Myocardial infarction or MI
2. Non CAD causes are variable and include ones that are not related to the cardiac ones

13. Elevated cTn – Non CAD conditions
Elevated levels of cTn are also found in non coronary artery disease (CAD) related conditions Like:
Critically ill patients with non CAD – 50%
Tachycardia %
Pancreatitis/heavy exercise %
Heart failure %
Bakshi et al; 2002 – Korff et al;2006

14. Diagnostic value of cTn
Detection and monitoring of the cTn is the new standard in the differential diagnosis of the :
Unstable angina and non ST elevation MI
It is also significant in the following conditions:
Acute MI and Myocardial re- infarction
Post procedural MI and
diagnosis of MI after non cardiac surgery
Braunwald et al;2000 -

15. Cardiac biomarkers - significance the features
These are the molecules released into blood after myocardial damage and enhance the ability of the clinician:
to manage the patient after chest pain. (blood, urine and tissues)
The important cardiac biomarkers are :
The Typical rise and gradual fall of cTn or :
A more rapid rise and fall in CKMB and others
Rama Chandran Vasan ;2006

16. Myocardial infarction (MI) - the definition
It is the death of an area of myocardium as a result of sudden and complete obstruction of blood supply
Most common cause of the MI is the occlusion of the coronary artery or one of its branches
MI is evaluated by the history; Physical examination, cardiac biomarkers, ECG, cardiac imaging

17. Criteria for MI – 2 Classes Expert consensus document
Criteria for the diagnosis of MI is divided into 2 according to the Expert Consensus Document (ECD)
ECD was agreed upon by the experts from the :
European Society of Cardiology (ESC), American College of Cardiology (ACC) and American Heart Association (AHA)
1. Criteria for an acute, evolving or recent MI
2. Criteria for the established MI

18. Diagnosis of MI by ECD criteria
Following is the ECD criteria for the :
1 Acute, evolving or recent MI
2. Established MI

19. Diagnosis of acute /recent / evolving MI
Diagnosis of acute /recent / evolving MI. (A) one of the biomarkers + ECG changes
Either one of the following criteria, satisfies the diagnosis for acute/evolving/recent MI
1. Cardiac Biomarkers:
Typical rise and gradual fall of cTn or
More rapid rise and fall (CKMB)
(one of cardiac bio markers- cTn – CKMB ) the

20. Diagnosis of acute/recent. B ECG changes/symptoms
At least one of the followings:
1. Severe pain/pressure in the chest
2. Development of pathological Q wave on ECG,
3. ST segment elevation or depression
4. Coronary artery intervention angiography /angioplasty
J Am Coll Cardiol Sep;36(3): –ESC/ACC/AHA

21. Normal Electrocardiogram - ECG

22. Pathological Q wave

23. MI – ST segment elevation

24. MI- ST segment depression

25. Criteria for the Established MI ECG and structural heart changes
Any one of the following criteria satisfies the diagnosis for the established MI.
1 Development of fresh pathological Q waves on serial ECG
3. Findings of a healed/healing MI on Echo - Imaging
Biomarkers may have been normalized
(1. New patho.Q wave 2. echo +imaging of healed infarcts)

26. Difference B/W Cardiac Troponins (cTn) and Creatine Kinase (CK- CKMB)
Serial NO
Cardiac Troponins
CKMB 1
Are non enzyme proteins
Are enzyme proteins 2
Are specific to cardiac myosites
Also present in skeletal muscles 3
Normal serum levels are too low to be detected, has no base line
Normal serum levels are detected – has base line 4
Majority is bound to cardiac myofilaments
Majority is unbound and fully Cytosolic 5
Rapid rise and gradual fall with
Late clearance
Rapid rise and fall in MI
early clearance 6
Elevated levels Predicts the adverse out come in CAD
No such property 7
Predicts the infarct size
Do not predict

27. Cardiac biomarkers- the time table