This document discusses cardiac biomarkers used in the diagnosis of acute myocardial infarction (AMI). It provides details on common biomarkers like CK-MB, myoglobin, and troponin and explains their normal ranges, onset times, peak levels, and duration in the blood. Troponin is highlighted as the most specific and sensitive marker for cardiac injury. The mechanisms, clinical applications, and limitations of cardiac biomarker testing are summarized.
Cardiac Biomarkers in the Diagnosis of Acute Myocardial Infarction
1. By
Dr.Anup Bhandari
JR 1 ,Department of Pathology,
S.R.T.R.M.C.Ambajogai
2. • “A is a substance used as
an indicator of a biologic state.
• It is a characteristic that is
objectively measured and
evaluated as an indicator of normal
biologic processes, pathogenic
processes, or pharmacologic
responses to a therapeutic
intervention.”
• --Wikipedia
3.
4.
5. • preexisting ST-segment • Gastroesophageal
elevation because of disease
ventricular aneurysm or • Pericarditis, pleuritis
by Q waves • Chest wall syndromes
• pacemaker rhythm • Pulmonary embolism
• or preexisting or newly • Aortic aneurism
developed bundle
• Herpes zoster
branch blocks (BBB).
6. • Diagnosing AMI/ACS
• Detecting myocardial damage whether due to AMI or
other cardiac process
• Risk-stratifying patients
• Commenting on Prognosis
– In ACS, pre and post PCI/reperfusion therapy
– Renal Disease
• Stressing interns, confusing residents and worrying
cardiology fellows
8. Test Normal Range
CK or CPK Normal 25-170 U/L
Creatinine
Phosphokinase
CK-MB < 5% MB
Myoglobin Normal < 85 ng/ml
LDH Normal 100-200 U/L
(Lactate LDH-1 -5
dehydrogenase) LDH- 1 is found primarily in
heart muscle and red blood
cells.
Troponin Normal < 0.01ng/ml
cTnT May be elevated by CRF
Troponin I Normal < 0.1 ng/ml
cTnI Not elevated by CRF
Most cardiac specific
9. Timing Summary
TEST ONSET PEAK DURATION
CK/CK-MB 3-12 hours 18-24 hours 36-48 hours
Troponins 3-12 hours 18-24 hours Up to 10 days
Myoglobin 1-4 hours 6-7 hours 24 hours
LDH 6-12 hours 24-48 hours 6-8 days
10.
11. • Typical rise and gradual fall (troponin) or
more rapid rise and fall (CK-MB) of
biochemical markers of myocardial necrosis
with at least one of the following:
• ischemic symptoms;
• development of pathologic Q waves on the
ECG;
• ECG changes indicative of ischemia (ST
segment elevation or depression);
• coronary artery intervention (e.g., coronary
angioplasty)
12. • Troponin is a complex of three regulatory
proteins that is integral to non-smooth
muscle contraction in skeletal as well as
cardiac muscle
• Troponin is attached to the tropomyosin
sitting in the groove between actin filaments
in muscle tissue
• three subunits, TnC, TnT, and TnI
– Troponin-C (calcium ions)
– Troponin-T (tropomyosin)
– Troponin-I (actin)
13.
14. :
– Cutoff is set at 99th percentile of a
normal reference population,
variation of less than 10%
– Since troponin levels are virtually
undetectable in normal subjects,
this 99th percentile corresponds to
<0.01(cTn T) ,0.1(cTn I)
– -heparin in sample can result in
lowered values
15.
16. Troponin Early Peak (Hrs) Duration Specficity Sensitivity
Rise(hrs) (Days)
Tn T 3-4 10-24 10-24 80% >98%
Tn I 4-6 1-24 4-7 95% >98%
• Therefore it has good utility for retrospectively
diagnosing AMI
• Remember, CK-MB returns to baseline by
17. chronic disease
detectable even if not acute
levels myocardial
damage
72-96 hour
peak TI infarct size
value
time to peak a lower cardiac event-
troponin >11 free survival rate and
with increased risk
hours of reinfarction
18. heart failure, myocarditis and pericarditis,
cardiomyopathy, cardiac contusion, defibrillation and
internal or external cardioversion,cardiac procedures
critical illnesses such as sepsis, Several toxins and
venoms, Carbon monoxide poisoning , primary pulmonary
hypertension, pulmonary embolism and acute
exacerbations of chronic obstructive pulmonary disease
(COPD), Seizures, end-stage renal disease, Strenuous
endurance exercise
19.
20. • SOS
• repeated at 2 and 72 hours later
• Assay times range from 5 to
30minutes
• TAT<60 min
• cTn T >0.1 ng/ml
• cTn I >1.0 ng/ml
21. An immunoassay is a biochemical test that
measures the concentration of a substance in
serum or urine, using the reaction of a
specific antibody (often monoclonal Ab) or
antibodies to bind to its antigen. To determine
a numerical result (as in cardiac biomarkers),
the response of the fluid being measured
must be compared to standards of a known
concentration. One of the most common
methods is to label either the antigen or the
antibody with an enzyme (EIA), radioisotope
(RIA), magnetic labels (MIA) or fluorescence
22.
23. False- False-
positive negative
interference of
heterophile circulating IgG-
antibodies class
autoantibodies
fibrin clots
microparticles
in specimens
analyzer
malfunctions
24. IMA • Increases within 6-10 min
• Used with ECG Or troponin
GPBB • Peaks earlier than CK-MB
• More sensitive early marker
MPO • Released from WBC granules
• Atheromatous plaque instability
26. Edge over other biomarkers
• improved time dependent sensitivity and
improved specificity
• first peak value 40 times the detection limit Vs
CK-MB only 6-9 times
• prognostic value of troponin in unstable
angina,reperfusion therapy
• Corelates with infarct size
• Reducing false positives
