Lecture 10: Ischemic Heart Disease Part 2 Flashcards
What is always the initial test for anyone presenting with chest pain?
EKG
How fast should an EKG be done if someone presents with ACS symptoms to the ER?
10 minutes!
What is the initial presentation of an EKG with ACS findings?
Hyperacute T waves
Only exists 20-30 minutes
What are the 3 types of cardiac enzymes we can order?
- Myoglobin
- CK-MB
- Troponin I, T (the best)
This comes AFTER EKG.
Why are troponins the preferred marker for myocardial study?
- Increases within 3-6 hours
- Peaks within 24-48 hrs
- Takes 5-14 days to recover.
- ONLY RELEASED when myocardial necrosis occurs.
How often should we repeat troponin?
- Initial presentation
- 90 Minutes
- 6-8 hrs after x3 or unil trending down.
What are we specifically looking for in serial troponin readings?
A trend.
What is considered a positive CK-MB?
> 5%
Not preferred test
What might cause a false positive of CK-MB?
- Exercise
- Trauma
- Muscle disease
- DM
- PE
What cardiac biomarker is the earliest marker for MI?
Myoglobin
Highly sensitive, but poor specificity.
Could appear within 2 hrs.
What is the order of enzyme elevation in ACS?
- Myoglobin
- CK-MB
- Troponin
- LDH
Trop takes longer to elevate.
What 3 lab levels may elevate as a result of ACS?
- Leukocytosis
- ESR
- CRP
What is the general minimum for doing an exercise stress test?
- Walk 5 minutes on flat ground
- 1-2 flights without stopping
What are the indications for a stress test?
- Confirm angina
- Determine severity of limitation
- Assess prognosis of known CAD and MI recovery
- Evaluate response to therapy
Who is an exercise stress test most useful for?
- Low pretest likelihood and normal baseline EKGs
- Best in young, females with atypical symptoms.
What is the max HR for a stress test and the finding that makes it positive?
- 85% of max HR (220-age)
- ST depression of 1mm = positive
When do you absolutely need to terminate a stress test?
- SBP drop of 10mm Hg from baseline
- Mod-severe angina
- Nervous system symptoms
- Poor perfusion
- Subject wants to stop
- Sustained Vtach
- ST elevation without Q-waves
What are the absolute contraindications to TMSTs? (treadmill stress tests)
- Acute MI within 2d
- High-risk, unstable angina
- Uncontrolled arrhythmias resulting in hemodynamic instability
- Severe, symptomatic AS
- Uncontrolled symptomatic HF
- Acute PE
- Acute myocarditis or pericarditis
- Acute aortic dissection
When do we add imaging to an exercise stress test?
Resting EKG is difficult to interpret (LBBB, baseline changes, low voltage)
What scan is associated with a nuclear stress test?
SPECT (single photon emission CT)
What adaptation can be added to an exercise stress test to look for regional wall motion abnormalities?
Stress echo
Why does a pharmacological stress test require imaging?
Poor sensitivity, so it requires an imaging modality.
What are the 3 vasodilators used for pharmacological stress tests?
- Adenosine
- Dipyridamole
- Regadenoson
Direct CORONARY ARTERY VASODILATION
Preferred agents.
What is the primary contraindication to pharmacological stress agents?
Bronchospasms
What are the 2nd line stress agents used in pharmacological stress tests?
- Dobutamine
- Atropine
Adrenergic stimulants
B1 and B2 stimulation.
Only used if you can’t use a vasodilator (i.e. asthma)
What is the definitive diagnostic procedure to evaluate CAD and heart muscle function?
Coronary angiogram.
What common medication MUST BE HELD for 48 hours prior to cath?
Metformin!!!!
Contrast = nephrotoxic
What is the prep required for a coronary angiogram?
- NPO 4-6 hrs
- Written consent
- IV NS to flush contrast
- Hold metformin for 48hrs to avoid contrast induced nephropathy
When is coronary angiography indicated?
- Life limiting stable angina
- High pretest likelihood
- Aortic valve disease
- Valve surgery
- Survivors of sudden death
- Chest pain of unknown etiology or idiopathic cardiomyopathy
- STEMI patients requiring immediate revascularization
If a patient has a contrast allergy, can we still perform coronary angiography?
If it is a life-threatening emergency, yes.
Add benadryl and steroids prophylactically.
What is a CXR mainly used for in chest pain?
R/o pulmonary causes
What must HR be for a CT of the coronary arteries?
Under 50 to prevent artifact.
What is the most sensitive and specific NON-invasive imaging modality for CAD?
CT Angiography
For inpatient workup of unstable angina, what are the diagnostic tests we should order?
- Low: obs
- Intermediate: stress test with nuclear imaging
- High: cath
What is the primary difference between unstable angina and NSTEMI?
Troponin is negative in unstable angina.
EKG is the same usually.
If we have ST elevation >= 1mm in two contiguous leads, what is the workup?
No labs, straight to cath lab!
What are the drug classes indicated for stable angina managment?
- NTG
- BB
- CCB
- Ranexa (Metabolic modulator)
What are the first-line therapies for unstable angina/NSTEMI/STEMI?
- Supplemental O2 (only if hypoxemic)
- Nitrates
- ASA (162-324mg chewable)
ASA is given regardless of fibrinolytic therapy.
If a patient has an ASA allergy, what is the alternative for them in ACS?
- P2Y12 inhibitors
- Clopidogrel
- Prasugrel
- Ticagrelor
After the first-line therapies for ACS managment, what are the next meds?
- Morphine/benzos for pain
- Oral BB within 24 hrs unless CHF, brady, or AVB
- ACEI within 24 hrs
- Statin within 48 hrs
Consider: CCB for persistent ischemia
What are the reperfusion goals?
- Door to balloon in 90 minutes
- Door to needle in 30 minutes
Preferred is PCI, but if not available, then we use tPA for thrombolysis.
What does NTG do?
- Nitrate conversion to nitric oxide, leading to cGMP activation and coronary vasodilation.
- Decreases SVR and preload
- First line for patients with ACS except IWMI.
IWMI involves the RV, which will affect preload too much if treated.
When should NTG be used in caution?
- Hypotension < 100
- Brady
- Tachy
- RV infarction
RV infarction already presents with decreased preload, and decreasing it further will bottom out a patient.
What is the shortest acting NTG?
SL
What is the main concern with using long-acting nitrates?
- Tachyphylaxis if no breaks are given.
- Need to dose at least 8-12 hours apart to prevent it.
- Long-term nitrates can lower angina threshold as well.
Avoid high doses!
What should you never give a nitrate with?
PDE-5 inhibitors!!!!!!!!!!!!!!!!!!!!!!!
Works on cGMP the same way.
What does morphine do in terms of the heart?
- Decreases sympathetic tone
- Decreases SVR
- O2 demand
Reduction of afterload.
Often used for refractory angina during ACS.
Why do we give chewable asa for ACS?
- Antiplatelet aggregation
- Stabilize plaque and prevent it from forming a big thrombus.
- Chewable ASA absorbs much more quickly.
What are the main concerns with ASA?
- PUD
- Allergy
- Bleeding disorders
Often treated with PPI.
What drug is bolused prior to a cardiac cath?
600mg of plavix
What do glycoprotein 2b/3a inhibitors do?
- Inhibition of platelet aggregation
- Supports PCI
- High risk patients only
Aggrastat
Integrilin
Reopro
What 3 situations might glycoprotein 2b/3a inhibitors be used?
- Ongoing ischemia despite ASA and P2Y12 inhibitor use
- Large thrombus during angiography
- Stabilize urgent CABG patients in place of using a P2Y12.
When are BBs indicated in regards to ACS?
- Added to post-MI patients that are STABLE
- Reduction in infarct size, rate, and life-threatening tachyarrhythmias
- Reduction in cardiac remodeling and enlargement
When are BBs NOT indicated?
- Acute CHF
- Heart Block
- Hypotension
What BBs are typically used in post-MI patients?
- Metoprolol tartrate
- Carvedilol
What is ranolazine?
(MOA, indication, danger)
- MOA: late Na channel blocker.
- Indication: Chronic, stable angina
- Danger: QT prolongation
500mg PO BID
What is the role of ACEis and ARBs post MI?
- Reduction in fibrosis and remodeling
- Preserve myocardium in setting of a MI
What other medications are indicated for post MI patients?
- Statins post ACS
- Warfarin for intracardiac thrombus or embolic events
- Aldosterone antagonists for LV dysfunction
- CCBs NOT usually used, 3rd line!!
What are the two formulations of fibrinolytics?
- Alteplase (Recombinant)
- Tenecteplase (genetically engineered)
What is the life-threatening complication that can occur due to tPA administration?
ICH
What must be done post-tPA?
- ASA
- AC with LMWH
How quickly does tPA needed to be administered for STEMI?
- Ideal: 30 minutes to ED arrival
- Reducion in mortality within first 3 hours of presentation.
CATH IS PREFERRED
If a patient requires fibrinolytics for a STEMI, what two medications must they be started on after?
- PPIs
- H2 Blockers
What are the absolute CIs to fibrinolytics?
- Prior ICH
- Known AVM
- Known malignancy
- Ischemic stroke within past 3 months (unless within past 3 hrs)
- Active internal bleeding
- Suspected aortic dissection
- Active bleeding or bleeding diathesis
- Significant closed head or facial trauma within 3 mo.
When is PCI indicated?
Unstable disease
GOLD STANDARD
What therapy follows PCI?
- Dual antiplatelet therapy (DAPT)
- P2Y12 receptor blocker + ASA for 3-12 months.
What exactly is a stent?
- Thin-wire mesh used to keep an artery open.
- Can contain drugs
- Supports the artery.
What is the caveat to a drug-eluting stent?
- Longer period of DAPT
- However, it is the preferred stent in PCI.
Drug-eluting gives off a drug slowly to help prevent cell proliferaiton.
What is atherectomy?
- Specialized catheter that removes plaque
- Requires DAPT post-procedure
When is CABG preferred for revascularization?
- Left main trunk artery stenosis
- Poor LV function
- Significant 3-vessel CAD or 2-vessel disease involving proximal LAD
- DM with focal stenosis in more than 1 vesse;
- Concomitant severe valvular disease that necessitates open heart surgery
- Diffuse disease not amenable to treatment with PCI
