2. • “A biomarker is a substance used as
an indicator of a biologic state”.
Morrow and de lomos three criteria for biomarkers
• Accurate repeated measurements at reasonable
cost
• Must provide additional information
• Should aid treatment
3. Characteristics of an ideal
biomarker
• Standardized
• High Sensitivity and Specificity
• Accurate
• Reproducible
• Easy to interpret
• Acceptable to patient
• Consistent and Cost effective
• Has an impact on clinical/risk
management
4. WHAT ARE CARDIAC MARKERS?
Located in the myocardium
Released in cardiac injury
Myocardial infarction
Non-Q-wave infarction
Unstable angina pectoris
Other conditions affecting cardiac muscle (trauma, cardiac surgery,
myocarditis etc.)
Can be measured in blood samples
5. History of Cardiac
Biomarkers
1954 - SGOT (AST)
1955 - LDH
1960 - CPK
1972 - CPK isoforms by Electrophoresis
1975 - CK - MB by immunoinhibition
1975 - Myoglobin
1985 - CK - MB Mass immunoassay
1989 - Troponin T
1992 - Troponin I
7. • CRP is Pentameric structure consisting of
five identical
subunits of 23-kDa.
• Its plasma levels can increase rapidly to 10,000x
levels.
• It is the most extensively studied marker of
inflammation. Despite some controversy regarding
its clinical use, it appears to be the most promising
to date.
• Although considered to be a general nonspecific
marker of inflammation, elevated baseline levels of
hsCRP are correlated with higher risk of future CV
morbidity and mortality among those with or
without clinical evidence of CVD.
High-Sensitivity
C-Reactive Protein
8. Clinical Uses
– Screening for cardiovascular risk in
healthy individuals
– Predictive value of CRP levels for disease
severity in pre- existing Coronary artery
disease
Elevated levels are predictive of
• Long-term risk of first MI
• Ischemic stroke
High-Sensitivity
C-Reactive Protein
9. • Low specificity
• No evidence that lowering CRP levels decreases CV risk
Industry and FDA staff guidelines 2005 had given clinical
cut off value as less than 1 mg/l as safe levels with hs-
CRP tests
CRP
Less than 1.0
mg/L 1.0-2.9 mg/L
Greater than 3.0
mg/L
Risk for CVD
Low
Intermediate
High
Limitations of CRP
10. • Soluble fragment CD 40 ligand.
• It is a signalling protein that reflects both inflammatory and
platelet interaction.
• ↑ levels of sCD40L is associated with ↑ risk of cardiac events
• However rise is also associated with many other
inflammatory conditions like RA, SCD, SLE etc.
• Furthermore, pre-analytical procedure such as anticoagulant
quantity, temperature, time and centrifugation speed
significantly affect the final result, which proves to be potential
barrier to practical application of test.
sCD40L
11. • Intermediary amino acid formed by the conversion of
methionine to cysteine
• Moderate hyperhomocysteinemia occurs in 5-7% of the
population
• Recognized as an independent risk factor for the
development of atherosclerotic vascular disease and
venous thrombosis
• Can result from genetic defects, drugs, vitamin
deficiencies
Homocysteine
12. • Homocysteine is implicated directly in vascular injury
including:
– Intimal thickening
– Disruption of elastic lamina
– Smooth muscle hypertrophy
– Platelet aggregation
• Proposed mechanisms by which it induces vascular injury
are leukocyte recruitment, foam cell formation, and inhibition
of NO synthesis.
• Normal levels : 3.7 – 13.9 µmol/L
Homocysteine
13. • Elevated levels of homocysteine appear to be an
independent risk factor, though less important than
the classic CV risk factors.
• Treatment includes supplementation with folate, B6
and B12.
Homocysteine
15. • Its high relative stability in plasma, have led to its potential use in the
clinical setting.
• Elevated level of PAPP-A are found in patients presenting with
unstable plaques, aggravated unstable angina and acute MI.
• It is also a reliable predictor of mortality in patients with chronic
stable CAD.
• FREE PAPP-A >1.74 mIU/L is considered abnormal
• Currently there is no standardised assay in widespread clinical use.
Pregnancy associated plasma
protein-A (PAPP-A)
16. • In the blood it mainly travels with LDL. Less than 20% is associated with HDL.
• It is produced by inflammatory cells and hydrolyzes oxidised phospholipids in LDL
• Two main sources of Lp-PLA₂ are :
1. which is brought from circulation into the intima bound to LDL
2. which is synthesised de novo by plaque inflammatory cells.
• Lp-PLA₂ is involved in the development of atherosclerosis and It is positively
correlated with increased risk of developing coronary artery disease.
• Its level in blood is measured by PLAC test, an assay which uses sandwich ELISA.
• Average value for females is 174 ng/mL
for males is 251 ng/ml
18. • Ischemia modified albumin is a marker formed after
damage in the N terminal region of the albumin in
ischemic conditions.
• This structural change leads to loss of its ability to bind
with transitional metals (cu/co).
• Endothelial or extracellular hypoxia, acidosis and free
oxygen radicals causes increase in IMA.
• IMA rises within minutes from onset of ischemia and
remains elevated for several hours after cessation of
ischemia.
Ischemia
Modified Albumin
19. it is used as diagnostic criteria for myocardial necrosis
that develops after CABG operation.
It is a non specific marker, since it is also reported to be
elevated in pulmonary infarction, critical limb ischemia
and cerebrovascular disorders.
Basically, it is used to rule out ischemia rather than
diagnosing the occurrence of ischemia. Which is helpful
in differentiating pain of Angina from Myocardial
Clinical uses of IMA :
20. • Heart type fatty acid binding protein is
a very stable low molecular weight (14-
15kDa) in the cytoplasm of myocardial
cells
• appearing as early as 1-3 hrs after onset and
peaking within 6hrs. It return to normal
levels with in 12-24hrs.
• Normal levels : 1.6 – 19 ng/ml
H-FABP
21. • H-FABP is 20 times more specific to cardiac muscle than
myoglobin
• H-FABP is recommended to be measured with troponin to
identify MI and ACS in patient presenting with chest pain.
• In addition to its diagnostic potential H-FABP also has
prognostic value. The risk associated with ↑ H-FABP is
dependent upon its concentration. Patients who were cTnI-
but H-FABP+ have more risk of morbidity and mortality
after 1 year follow up than those with cTnI+HFABP-.
H-FABP
23. • Troponin is a complex of three regulatory
proteins (Troponin C, Troponin I and Troponin T)
that is associated with muscle contraction in
skeletal and cardiac muscle.
• Cardiac troponin is slightly different from
skeletal troponin structurally hence serve as a
potent and specific marker for cardiac disease.
Cardiac Troponins
25. Individual subunits serve different functions:
• Troponin C binds to calcium ions to
produce a conformational change in TnI
• Troponin T binds to tropomyosin, interlocking them
to form a troponin-tropomyosin complex
• Troponin I binds to actin in thin myofIlaments to
hold the troponin-tropomyosin complex in place
• Usually, Troponin is not detectable in
healthy individual.
Cardiac Troponins
26. • It is extremely useful in patients who do not seek
attention in the 2 to 3 days window when CK-MB is
elevated.
Rise : with in few hours after
onset of chest pain Peak : 2 days
returns normal : 7-10 days
• cTnT may show a biphasic release in some patients
with a first peak occurring during first 24 hr of onset of
symptom and second peak on appx. 4th day after
admission.
• TnT has cardiac as well as skeletal muscle source.
cTnT
27. • It is cardiac specific because it has additional amino acid
residue
on its N-terminal that are non existent in skeletal muscle.
Rise : b/w 4-6 hr after onset of pain
Peaks : 12-18 hrs
Returns normal : 6 days
• Its measurement is advantageous over CK-MB as it is not
found in detectable amount in serum of patients with
multiple injuries, renal disease and in those with acute and
chronic skeletal muscle disorders.
cTnI
30. • Creatine kinase (CK) is a cytosolic enzyme involved
with the transfer of energy in muscle metabolism. It
catalyses the conversion of creatine to phospho-
creatine degrading ATP to ADP.
• CK is a dimer composed of two subunits B (brain
type) and M (muscle type), resulting in three
isoenzyme:
CK-BB (CK1) : is of brain origin, found in blood only
when BBB is damaged.
CK-MB (CK2) : it is relatively specific for myocardial
origin
CK-MM (CK3) : it is found primarily in skeletal muscle
CREATINE KINASE:
CK-MB
31. CREATINE KINASE:
CK-MB
• CK-MB is the most cardiac-specific CK isoenzyme
• Proportion of CK-MB varies in skeletal & cardiac muscle
• In normal population CK-MB < 6% Tot CK
• Sensitive marker with rapid rise & fall
• More specific than Tot CK but has limitations
• “Gold standard” biochemical marker for past few decades
• “There is no place for measurement of CK-MB by
electrophoretic or immunoinhibition methods in the
21st century laboratory” Jacobs, Lab Test Handbook 5th Ed 2001,157
Only CK-MBmass should be measured
32. It is a valuable tool for the diagnosis of MI because of
its
relative high specificity for myocardial damage.
Rise : 4-6 hrs after onset of symptoms
Peak : 12 hrs
Return to normal : 24-36 hrs
Can be used to indicate early re-infarction if level
normalizes
and then increases again.
CK-MB :
33. CK-MBmass RELATIVE INDEX (%RI)
% RI = (CK-MBmass / Tot CK activity)
x 100
• Increased RI suggests myocardial origin
• RI > 3 – 6 % with Tot CK activity elevated suggests
myocardial
necrosis
34. • Small-size heme protein found in all tissues mainly assists
in oxygen transport
• It is released from all damaged tissues
• Its level rises more rapidly than cTn and CK-MB.
• Released from damaged tissue within 1 hour
• Normal value: 17.4-105.7 ng/ml
• Timing:
– Earliest Rise:
– Peak
– Return to
normal:
1-4 hrs
6-9 hrs
12 hrs
Myoglobin
35. • Acute myocardial infarction
• Skeletal muscle damage,
muscular dystrophy,
inflammatory myopathies
• Renal failure, severe uremia
• Shock and trauma
CONDITIONS FOR
MYOGLOBIN INCREASE :
36. *if myoglobin concentration remains within the reference
range 8 hours after the onset of chest pain, AMI can be ruled
out essentially.
*because of its rapid clearance by the kidney, a
persistently normal Mb concentration will rule out
reinfarction in patient with recurrent chest pain after AMI
*Rapid monitor of success of
thrombolytic therapy
DRAWBACKS
• Due to poor specificity, myoglobin levels do not always
predict myocardial injury
Clinical usefulness of
myoglobin :
37. NEW GENERATION
CARDIAC MARKERS
• Myoglobin
– Currently earliest marker
– Like as total CK its not cardio-
specific
• Troponins
– Cardio-specific
40. • ANP is released primarily in response to atrial wall stretching and
intravascular volume expansion.
• BNP is mainly secreted by the ventricles
• CNP is found predominantly in the brain and also synthesized by
vascular endothelial cells
natriuretic peptides
41. • Circulating levels of BNP are raised in patients
with cardiovascular or renal disease
• BNP is More important than ANP in heart failure
• Greatest proportion of circulating BNP is thought
to come from the ventricles (left)
BRAIN NATRIURETIC
PEPTIDE
(BNP)
42. • BNP and the terminal fragment of its prohormone (NT-
proBNP) are released on ventricular stretch or stress to the
myocyte in the absence of the necrosis.
• Therefore, BNP is increased in diseases characterised by an
expanded fluid volume (e.g. CHF, renal failure,hepatic cirrhosis
etc.)
• BNP has circulating T₁/₂ of 20 minutes, so it is indicative of
snapshot of myocardial function, while NT-proBNP has T₁/₂ of
90 minutes giving a longer view of myocyte .
BRAIN NATRIURETIC
PEPTIDE (BNP)
43. • Age
• Arrhythmias
• Cardiomyopathy:
hypertrophic,
ischemic, or dilated
• Congestive heart failure
• Coronary artery disease
• Gender
• Hypertension
• Left ventricular diastolic
dysfunction
• Pulmonary embolism
• Renal failure
• Right heart failure
• Right ventricular
overloading: fluid, or
pressure overloading
• Sepsis or septic shock
• Sepsis-related
myocardial dysfunction
Conditions or factors commonly associated
with B-type natriuretic peptide or N-terminal-
pro-B-type natriuretic peptide elevations
45. • miRNAs are appx. 20-25 nucleotide long non coding RNAs, that
negatively regulate or inhibit gene expression
b
y binding to sites in the untranslated regions of targeted
messenger RNAs.
miRNA
Dr.Bikash Kr.Chaudhury
46. • miRNAs that regulates cardiovascular system can be divided into
4 groups :
1. miRNA regulating endothelium function and angiogenesis :
miR126, miR17-92 cluster, miR130a, miR221, miR21
2. cardiac myocyte specifIc mRNA : miR208a
3. cardiac myocyte and skeletal muscle miRNA : miR1, miR133a,
miR499
4. smooth muscle miRNAs :miR143, miR145
miRNAs hold promise as very specific and accurate
marker of cardiac dysfunction.
miRNA
47.
48. SUMMARY
• “Cardiac Enzymes” are obsolete
• Medical & laboratory progress has required a redefinition of Cardiac
Events
• Cardiac Troponin and myoglobin now play a vital role in diagnosis
of AMI
• Cardiac Troponins play an important role in the risk stratification of
ACS patients
• Elevated Troponin levels in patients without ECG changes & with normal
CK-MB levels may identify patients at increased risk of cardiac events
49. SUMMARY
• Elevated Troponins in the absence of clinical signs of
ischaemic heart disease require consideration of other
causes of cardiac injury
• Need for rapid TAT & reliable cardiac markers
• Additional roles for cardiac markers in:
– Reperfusion monitoring
– Infarct size/prognosis
– Intra/post-operative MI (non-cardiac/cardiac surgery)
• Evolving laboratory role in the evaluation of cardiac
disease particularly in the areas of cardiac dysfunction
& general biochemical or genetic risk factors
