Cardiac Enzymes

Question 1

How do you distinguish between a STEMI and NSTEMI?

Answer 1

EKG

Question 2

How do you distinguish between UA and NSTEMI?

Answer 2

Cardiac Enzymes

Question 3

What are cardiac enzymes?

Answer 3

When there is an infarction of myocardial cells the membrane integrity is disrupted causing leaking of macromolecules into the peripheral circulation where they are detected.

Question 4

Ideal Biomarker Requirements:

Answer 4

• High Specificity
• High Sensitivity
• Release and Clearance kinetics provide expedient diagnosis
• Measured level is in direction proportion to the extent of myocardial injury
• Commercially available, easy to perform

Question 5

This cardiac enzyme is highly specific and sensitive for MI.

It will rise in 3-12 hours
Peak at 24 hours
Return to normal in 5-14 days

Answer 5

Troponin I

Question 6

This cardiac enzyme is highly specific and sensitive for MI.

It will rise in 3-12 hours
Peak at 12-48 hours
Return to normal in 5-14 days

Answer 6

Troponin T

Question 7

When are troponin levels more beneficial?

Answer 7

6+ hours post-MI

Question 8

When do you need to reassess Troponin?

Answer 8

6-12 hours after symptoms began

Question 9

T/F: Troponin levels are not useful for late diagnosis of MI

Answer 9

False, they are useful.

Question 10

Negative Troponin Test indicates:

Answer 10

Low Risk of Death or MI within 30 days

Question 11

Positive Troponin Test indicates:

Answer 11

Strong Independent Predictor of Mortality and Serious Adverse Outcomes

Question 12

Tropinin turn around time?

Answer 12

9-12 minutes

Question 13

If a patient comes in with ACS symptoms, regardless of EKG findings, if there are negative troponins at least twice, how would we categorize this?

Answer 13

Unstable Angina

Question 14

If a patient comes in with ACS symptoms, ST/T Abnormalities (not Elevation) EKG findings, if there are positive troponins at least once, how would we categorize this?

Answer 14

NSTEMI

Question 15

Causes of Troponin Elevation other than MI

Answer 15

• CHF
• Tachyarrhythmia, heart block
• Endurance Exercise
• Cardiomyopathy (CM)
• Myocarditis, Pericarditis
• Blunt Chest Trauma
• Pulmonary Embolism
• Renal Failure
• Severe Sepsis
• Aortic Valve Disease
• CVA
• Cardiotoxic Drugs

Question 16

This enzyme is found in multiple places throughout the body, including: brain, lungs, GI, skeletal and cardiac muscle. It is subdivided into different groups.

Normal Range:

Answer 16

Creatine Kinase

Question 17

CK found in brain, lungs, and GI

Answer 17

CK-BB

Question 18

CK found predominantly in cardiac muscle and some skeletal muscle

Answer 18

CK-MB

Question 19

CK found in skeletal and cardiac muscle

Answer 19

CK-MM

Question 20

______ of CK increases diagnostic specificity.

Answer 20

Fractionation

Question 21

This is the most specific of the CKs for cardiac muscle.

It rises in 3-12 hours
Peaks at 24 hours
Returns to Baseline in 2-3 days

Answer 21

CK-MB

Question 22

False Positives of CK-MB could be due to

Answer 22

• Trauma
• Skeletal Muscle Injury
• Surgical Procedures

Question 23

What is better than CK-MB testing the same thing?

Answer 23

Monoclonal Antibody Assays (More accurate)

Question 24

How do you calculate the Relative Index for CK-MB?

Answer 24

[Measure CK-MB (ng/mL) x 100]/Total CK Activity (IU/L)

Question 25

What is the point of calculating the Relative Index?

Answer 25

Can assist in differentiating False Positives

Question 26

Rule of Thumb to determine if Postiive CK-MB is due to skeletal muscle damage or not?

Answer 26

A ratio of less than 3 is consistent with a skeletal muscle source.

Question 27

A Relative Index > 5 would indicate what?

Answer 27

Myocardial Necrosis

Question 28

This cardiac enzyme is a low molecular heme protein found in cardiac AND skeletal muscle.

It rises in 1-4 hours
Peaks in 6-7 hours
Returns to normal within 24 hours.

HIGHLY Sensitive to MI, but NOT specific

Answer 28

Myoglobin

Question 29

False Positives of Myoglobin could be due to:

Answer 29

• Skeletal Muscle Injury
• Trauma
• Renal Failure

Question 30

Which two tests are no longer recommended for MI?

Doubt we need to know this.

Answer 30

LDH

AST