Cardiac Biomarkers

Question 1

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.

Answer 1

A biomarker

Question 2

substances released from heart muscle when it is damaged as a result of myocardial infarction

Answer 2

Cardiac markers

Question 3

has been shown that cardiac markers can be released from cardiac tissue as a result of

Answer 3

damage from processes other than MI

Question 4

TRIAD Diagnosis of Acute Myocardial Infarction

Answer 4

• Chest Pain: highly variable and subjective
• ECG: Objective ST or T-wave changes
• Biomarker elevations: Objective data defining ACS/AMI

Question 5

Which Biomarkers?

Answer 5

CK (CPK)
CK-MB
Troponin-I/T
LD (LDH)
Myoglobin
ALT/AST

Question 6

1st Marker in response to AMI ?

0 - 1/2 day to be detected.

Answer 6

CK-MB isoforms

Question 7

2nd Marker(s) in response to AMI ?
1 day to be detected

Answer 7

CK-MB

Cardiac Troponin

Question 8

The CK enzyme consists of two subunits

Answer 8

B (brain type) or M (muscle type), Making three different isoenzymes:

1. ) CK-MM
2. ) CK-BB and
3. ) CK-MB

Question 9

Skeletal muscle expresses

Answer 9

CK-MM (98%) &

CK-MB (1%)

Question 10

The myocardium expresses

Answer 10

CK-MM (70%) &

CK-MB (30%)

Question 11

CK therefore, lacks specificity for cardiac damage and needs to be augmented with ?

Answer 11

MB fraction and Relative Index (RI) to indicate true cardiac damage

Question 12

(In cardiac as well as other tissues, phosphocreatine serves as

Answer 12

as an energy reservoir for the rapid regeneration of ATP)

Question 13

Creatine kinase (CK/CPK) is an enzyme expressed in a number of tissues. 
How does it Function?

Answer 13

it catalyses the conversion of creatine to phosphocreatine degrading ATP to ADP

Question 14

CK Needs _______ increase with simultaneous increase in CK-MB to be diagnostic for MI

Answer 14

> two-fold

Question 15

CK fluctuation in levels in regards to time?

Answer 15

• Increases 4-6 hours after onset of MI
• Peak activity is at 18 to 24 hours
• Usually has returned to baseline levels by 36 hours

Question 16

False positive (for MI) CK elevation can be seen in:

Answer 16

• Significant skeletal muscle injury
• Significant CNS damage (Stroke/Trauma)
• Occasionally from GI, renal, urologic disease

Question 17

*elevations of CK secondary to non-cardiac causes have been noted to increase following a flatter curve

Answer 17

rising and disappearing at a slower pace that a cardiac source

Question 18

CK-MB fluctuation in levels in regards to time?

Answer 18

Begins to rise 4-6 hours after onset of infarction
Peaks at about 12 hours
Returns to baseline at 24-36 hours

Question 19

What enzyme has a High specificity for cardiac tissue damage?

Answer 19

CK-MB

Question 20

CK-MB Can be used to indicate early re-infarction if ?

Answer 20

level normalizes and then increases again

Question 21

False positive (for MI) CK-MB elevation can be seen in:

Answer 21

Significant skeletal muscle injury

• Cardiac injury for reason other than MI
• Cardioversion,
• Defibrillation (ACLS CPR/ICD firing)
• Blunt chest trauma (MVA/Sports injuries)
• Cardiac AND non-cardiac surgical procedures
• Cocaine abuse (vasospasm, tachycardia, - perfusion/demand mismatch)
• Non often elevated in myocarditis, unless severe

Question 22

Cardiac specific forms of Troponins that are immunologically separable?

Answer 22

Troponin T (TpnT)
Troponin I (TpnI)

Question 23

• Regulatory proteins in striated muscle
• Responsible for calcium-modulated interaction
• Exist in a number of isoforms

Answer 23

Troponins

Question 24

Troponin is a complex

Answer 24

of three regulatory proteins that is integral to non-smooth muscle contraction in skeletal as well as cardiac muscle

Question 25

Troponin is attached to the

Answer 25

tropomyosin sitting in the groove between actin filaments in muscle tissue

Question 26

Troponin has three subunits,

Answer 26

TnC, TnT, & TnL

Question 27

Troponin-C binds to

Answer 27

calcium ions to produce a conformational change in TnI

Question 28

Troponin-T binds to

Answer 28

tropomyosin, interlocking them to form a troponin-tropomyosin complex

Question 29

Troponin-I binds to

Answer 29

actin in thin myofilaments to hold the troponin-tropomyosin complex in place

Question 30

Thus far, studies have failed to find a source of Troponin-I outside the heart, but have found some Troponin-T in skeletal muscle Because of it’s increased specificity, our lab uses

Answer 30

Troponin-I

Question 31

heparin in blood sample can result in lowered values of what?

Answer 31

Troponin

Question 32

Troponin-I levels begin to rise

Answer 32

2-3 hours after onset of MI

Question 33

80% of patients with AMI will have positive values at

Answer 33

3 hrs

Question 34

Elevations in Troponin-I and Troponin-T can persist for up to

Answer 34

10 days after MI

Question 35

What is a good utility for retrospectively diagnosing an AMI ?

Answer 35

Troponin

Question 36

Remember, CK-MB returns to baseline by

Answer 36

48 hrs

Question 37

Troponin release can also be precipitated by

Answer 37

other conditions that cause myocardial damage

Question 38

Degree of elevation of Troponin value can give

Answer 38

prognostic information

Question 39

Some data suggest that the _______ peak TI value correlates with infarct size.

Answer 39

72-96 hour

Question 40

Used in the past along with aminotransferases to diagnose AMI. It is non-specific for cardiac tissue, which contains LD-1. However, pancreas, kidney, stomach tissue and red cells also contain LD-1

Answer 40

LDH

Question 41

In the setting of AMI, What is the LDH timing?

Answer 41

Onset: 6 - 12 hrs Peaks: 24 - 48 hrs Duration: 6 - 8 days

Question 42

Ubiquitous small-size heme protein released from all damaged tissues. Increases often occur more rapidly than TI and CK. Not utilized often for AMI/cardiac damage assessment because of its very rapid metabolism (short plasma half-life) causing short burst increases that are difficult to assess clinically, as well as its lack of specificity for cardiac tissue.

Answer 42

Myoglobin

Question 43

Used as surrogate markers of cellular damage in the past. Very non-specific so not used for assessment of myocardial damage any longer

Answer 43

ALT/AST

Question 44

H-FABP

Answer 44

Heart-type fatty acid binding protein

Question 45

The major protein responsible for O2 supply of striated | muscle.

Answer 45

Myoglobin | Early detectable, more sensitive but non-cardiospecific