Cardiac Biomarkers

Substances that are released into blood when heart muscle has been damaged

What are cardiac biomarkers?

Acute coronary syndromes (ACS) and congestive heart failure

Cardiac biomarkers are used for evaluation of...

Troponin and CK-MB

Cardiac biomarkers used for acute coronary syndrome (ACS)

Brain natriuretic peptide (BNP)

Cardiac biomarkers used for congestive heart failure (CHF)

troponins

When muscle dies, ___________ are released

I (cTnI) and T (cTnT)

Two types of cardiac troponins that can be separated

acute coronary syndrome (ACS)

Troponins are most commonly used to evaluate...

STEMI, NSTEMI, and unstable angina

What does ACS include?

1. Detect reperfusion after percutaneous coronary intervention (PCI)

2. Estimate MI size after 4 weeks

3. Inversely related to left ventricle (LV) function

4. Detect intraoperative MI

5. Evaluate severity of pulmonary embolus

6. Indicate ventricular strain if persistently elevated in CHF

What are some other uses for troponins?

2-3 hours

Troponin levels become elevated how long after myocardial injury?

6 hours

Up to how long can it take to see a rise in troponin levels?

Serial cardiac enzymes

What is often ordered to compensate for the long period in which it takes to see elevations in troponin levels?

3 sets of cardiac enzymes taken 6-8 hours apart over 24 hours

What are serial cardiac enzymes?

10-14 days

How long can troponin levels remain elevated?

Renal failure (false elevation), CHF, pulmonary embolism (PE), cardiac pacing/arrythmia, hyper/hypotension, or myocarditis

What other things can elevate troponin levels (other than ACS)?

Take to cath lab to look for MI to decide between percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG)

What is the procedure if an individual has ACS symptoms and elevated troponin?

No MI

What does it mean if an individual has ACS symptoms but 3 sets of normal troponins?

High sensitivity cardiac troponins (hs-cTn)

Newer type of troponin able to detect cardiac troponin in 50% of the population and being used to develop Accelerated Diagnostic Protocols for ACS pathways in EDs and hospitals

CK-MB

Enzyme found mostly in the heart, but a small amount is found in skeletal muscles

Creatine kinase isoenzyme

What does CK stand for?

3-6 hours

Elevations in CK-MB are present _______________ after infarction

12-24; 12-48

CK-MB levels peak ______________ hours after damage and return to normal ______________ hours after damage

Quantifying degree of MI and timing of onset of infarction

What is CK-MB useful for?

CK-MM

Found mostly in skeletal muscle, and a small amount in the heart

CK-BB

Found in the brain and lung

1. Acute MI

2. Cardiac aneurysm surgery

3. Cardiac defibrillation

4. Myocarditis

5. Ventricular arrythmias

6. Cardiac ischemia

What can elevate CK-MB levels in ACS?

1. IM injections

2. Exercise/recent surgery

3. Early pregnancy

4. Increase in muscle mass

5. Some meds

What non-ACS events can elevate CK-MB levels?

1. More specific for cardiac muscle injury

2. Elevated sooner and longer after cardiac muscle injury

3. More sensitive for muscle injury

Why are troponins better than CK-MB?

Natriuretic peptides

Neuroendocrine peptides that oppose activity of the renin-angiotensin system and are used to determine if heart failure is present in a patient

Atrial or ventricular stretch

What are natriuretic peptides released in response to?

Vasorelaxation, inhibition of aldosterone secretion from the adrenals, and inhibition of renin secretion from the kidneys to increase natriuresis and decrease blood volume

What does the release of natriuretic peptides cause?

BNP (brain natriuretic peptide) and NT or N-terminal pro-BNP

What are two natriuretic peptide tests?

interchangeably

BNP and NT-pro-BNP can be used _______________, it just depends on the laboratory and their procedures

left ventricular stretch/pressure; 93; 74; 65

Increased amounts of BNP and NT-pro-BNP are released in response to _________________, they are ______________% sensitive for heart failure, but their specificity is at ____________% and ______________%

More severe HF

Increased BNP or NT-pro-BNP =

Atrial natriuretic peptide (ANP)

What is released from atrial heart muscle, can diagnose HF, but is not often utilized?

Aid in DDx of dyspnea (SOB) and in HF risk stratification

What are some used for BNP?

Gradual decrease with treatment

If acute HF, what do you want to see with BNP levels over time?

Worse prognosis

What does it mean if BNP levels do not decrease over time after acute HF?

HF is unlikely

A BNP value of less than 100 indicates...

some degree of CHF is very likely

A BNP value more than 500 indicates...

pretty much nothing (can't help either way)

A BNP between 100 and 400 indicates...

Age of patient

What does NT-pro-BNP take into consideration that BNP does not?

HF, MI, systemic hypertension, heart transplant rejection, and cor pulmonale

What causes elevations in BNP?

SOB and lower extremity edema

What are 2 major signs of CHF?