EXAM #2: MI I & II Flashcards
What does a MI typically result from?
Rupture/erosion of a VULNERABLE PLAQUE and the inflammation/pro-coagulation that follows
What is Acute Coronary Syndrome (ACS)?
Spectrum of clinical events that follow plaque rupture:
1) Unstable angina
2) Non-STEMI
3) STEMI
Do most plaque ruptures result in clinical events?
NO
What is the difference between NSTEMI and STEMI, in terms of the severity of coronary occlusion?
NSTEMI= partial occlusion of the coronary artery
STEMI= complete occlusion of coronary artery
What are the lab and ECG features that are diagnostic for an acute MI?
1) Elevation of cTn in setting of ischemia
2) ST changes or new onset LBBB
What are the ECG and echo features of a prior MI?
1) Q-waves
2) Evidence of loss of ventricular wall function
What are the three classifications/types of an MI?
1) Spontaneous MI caused by primary coronary event
2) MI secondary to supply/demand mismatch
3) Sudden cardiac death in setting of suspect MI
What are the characteristics of a stable atherosclerotic plaque?
- Thick fibromusuclar cap
- Few inflammatory cells
- Intact endothelium
What are the characteristics of an unstable/vulnerable atherosclerotic plaque?
- Thin fibromuscular cap
- Copious inflammatory cells
- Eroded endothelium
- Protruding Ca++
Where does atherosclerotic plaque rupture typically occur?
“Shoulder region” of the plaque
What “background” predisposes a vulnerable atherosclerotic plaque to ACS?
- Proinflammatory
- Procoagulant
How does a coronary artery remodel in response to atherosclerosis?
“Positive remodeling”
*Diameter of artery gets bigger to accommodate the plaque
What are the possible manifestations of a MI on cardiovascular physical exam?
1) Paradoxically split S2 from LV dysfunction
2) S4 from stiff LV
3) S3 with LV dysfunction/HF
4) New onset of MR
What is the Killip Classification?
Risk stratification tool for decompensated HF from acute MI
What is a Killip Class I?
- No rales
- No S3
What is a Killip Class II?
- Rales over less than 50%
or
-S3
What is a Killip Class III?
Rales in over 50% of lung fields
What is a Killip Class IV?
Shock
In what patient populations do you need to have an increased index of suspicion for acute MI?
1) DM
2) Women
3) Elderly
All present atypically and with more dyspnea, nausea/vomiting, or fatigue
What do you need to do for any DM patient that is “just not feeling right?”
ECG
What are the major lethal differential diagnoses for chest pain?
1) MI
2) PE
3) Pneumothroax
4) Acute aortic syndromes
- Dissection
- Perforated ulcer
- Intramural hematoma
What is the most sensitive and specific serum biomarkers of myocyte injury?
Cardiac specific troponin (cTn)
What is the clinical utility of CK-MB as a biomarker?
Differentiating timing
E.g. if a patient has chest pain a week ago and today–CK-MB elevation will correlate with acute MI today
What imaging should you get for a patient with chest pain?
1) CXR– r/o pneumothorax
2) Echo– wall motion and r/o aortic dissection
3) Nuclear SPECT
4) CT Cornary Angiography
On CXR, what is an indication of an aortic dissection?
Widened mediastinum
What is the first thing to do with a patient complaining of chest pain?
ECG
Goal is to obtain within 10 minutes of arrival and dictates further decision-making
What do you need to remember about the differences between ST depression and ST elevation?
ST depression does NOT correlate/ localize to an anatomic territory
What is the current guideline for the immediate treatment of a-fib with with re-entry tachycardia (underlying WPW)?
- Amiodarone (stable)
- Cardioversion (unstable)
If a patient presents with STEMI, what do you need to plan for?
Plan for IMMEDIATE reperfusion
What anti-platelet medication should all patients with STEMI get?
4x 81mg ASA
What are the main classes of medical therapy for acute MI?
1) Anti-platelet
2) Anticoagulant
3) Anti-ischemic
Practically, what should happen for every patient with acute MI?
1) Oxygen–lowest flow to keep O2 sat. at 90-92%
2) ASA (325mg)
3) Sublingual NTG
4) Anticoagulant e.g. Clopidogrel
What is the second line medication to consider in a patient with angina refractory to NTG?
Beta-blockers e.g. IV metoprolol
*Best for patient that is tachycardic and hypertensive
What are the three zones in a MI?
1) Zone of infarct
2) Zone of injury
3) Zone of ischemia
What is the most common cause of inferior MI? What is secondary?
1) RCA
2) LCX
What can result in transient AV block in inferior MI?
- Inferior MI is associated with high vagal tone
- Vagotonia can induce AV block that is transient
What infarction is associated with inferior MI?
RV
What PE sx. are seen with RV infarction?
1) JVD
2) Hypotension
3) Clear lung fields
Note that LAD occlusion with impaired wall function will caused CRACKLES in the lung fields
What can you do to confirm a RV infarction?
V4R
What medications should be avoided or used with caution in a RV infarction?
1) NTG
2) Beta-blockers
Note that trying IV fluid initially can be helpful–be sure that lung are clear
What is the clinical utility of thrombolytic therapy?
Cath. lab not available within 90 min of first medical contact
What are the absolute contraindications to thrombolytic therapy?
1) Prior ICH
2) Known cerebral vascular lesion
3) Known malignant intracranial neoplasm
4) Ischemic stroke within 3 months
5) Active bleeding/ bleeding diathesis (NOT menses)
6) Head/facial trauma within 3 months
7) Intracranial or intraseptal surgery within 2 months
8) Severe uncontrolled HTN
Should you give patients thrombolytics in NSTEMI?
NO–these are CONTRAINDICATED
How does the medical management of NSTEMI differ from STEMI?
1) More aggressive with initial Beta-blocker therapy
2) GP IIb/IIIa inhibitor for refractory angina
How does the clot type differ between STEMI and NSTEMI?
STEMI= fibrin rich “red’
NSTEMI= platelet rich “white”
What are the factors that would make you send a patient with NSTEMI to the cath lab?
1) Elevated cTn
2) Dynamic ST changes
3) Recurrent sx.
4) Low EF
What should be done for patients post-MI?
1) Assess EF with transesophageal echo
2) Assess/address risk factors
3) Educate about event and new lifestyle
4) Cardiac rehab
Outline post-MI medical therapy.
1) ASA for life
2) P2Y12 inhibitor for 1x year
3) Beta-blocker
4) ACE inhibitor if EF under 40%
5) Aldosterone antagonist for EF less than 40%
6) High intensity statins
7) PRN NTG
