Acute STEMI

Question 1

Most common cause of acute ST Elevation Myocardial Infarction (STEMI).

Answer 1

Destabilization of an atherosclerotic plaque leading to a thrombus formation that occludes coronary vasculature.

Question 2

What are two minor causes of acute STEMI and what treatment is contraindicated?

Answer 2

1. Embolic Phenomenon
2. Thoracic aortic dissection involving coronary vasculature

Thrombolytic therapy contraindicated.

Question 3

2 acute coronary syndromes that do not cause ST elevation.

Answer 3

1. Unstable Angina

2. NSTEMI

Question 4

What three criteria are involved in making acute STEMI diagnosis?

Answer 4

Dx: must have at least 2/3

1. Symptoms (chest discomfort)
2. EKG findings
3. Serum Cardiac Markers (usually take cpl hours to rise to detectable levels)

Question 5

First cardiac marker to arise after MI.

Answer 5

Myoglobin

Question 6

Most specific cardiac marker to rise in serum after an MI.

Answer 6

Troponin I

Question 7

What are three treatments for acute STEMI that work to lower the heart’s O2 demand?

Answer 7

1. Bed Rest
2. NPO until stable
3. Decrease Double Product (use beta blockers, digoxin)

Double Product = systolic bp x HR

Question 8

What are three treatments for acute STEMI that work to raise O2 supply to the heart?

Answer 8

1. Relieve Pulmonary Vascular Congestion (diuretics, IV NTG, MgSO4)
2. Acute Revascularization (thrombolytic therapy, catheter, CABG)
3. Intra-aortic balloon pump

Question 9

Why does thrombolytic therapy carry the risk of arrhythmia?

Answer 9

Reperfusion of the heart tissue can result in reperfusion injury which sends the heart into arrhythmia.

Question 10

Which of the four thrombolytic agents are double dose and which are single dose?

Answer 10

Double: t-PA and r-PA
Single: TNK-tPA and n-PA

Question 11

What are the time frames for use of thrombolytic therapy efficacy after the onset of MI symptoms?

Answer 11

Best if used 12 hrs unless symptoms come and go (“stuttering”)

Question 12

What are two EKG findings that promote thrombolytic therapy use for acute STEMI?

Answer 12

1. STE of greater than 1mm in 2 or more contiguous precordial OR limb leads
2. New (or presumed new) LBBB

Question 13

What are 5 contraindications for thrombolytic therapy treatment for STEMI dealing with the head?

Answer 13

1. Prior Intracranial hemorrhage (ICH)
2. AVM
3. Malignant Intracranial Neoplasm
4. Ischemic stroke in last 3 months
5. head or face trauma in last 3 months

Question 14

What are 2 non-cranial contraindications to thrombolytic therapy for STEMI treatment?

Answer 14

1. Suspected Aortic Dissection

2. Active bleeding (excluding menses)

Question 15

What are the two methods of mechanical revascularization and the indications for using them?

Answer 15

1. Catheter based intervention
   - used if can’t do thrombolytic therapy
   - used in cardiogenic shock
2. CABG
   - used in patients that can’t have catheters
   - pts. with mechanical MI complications

Question 16

Morphine is an adjunctive therapy for acute STEMI. When is it contraindicated?

Answer 16

Don’t use morphine in right sided heart failure

Question 17

What is a contraindication for using IV NTG to treat acute STEMI?

Answer 17

Right ventricular infarct

Question 18

3 medications to avoid in acute STEMI.

Answer 18

1. Short-acting calcium channel blockers (nifedipine)
2. Lidocaine
3. IV magnesium
   (lidocaine and IV mag can cause R on T phenomenon)

Question 19

When do most mechanical complications of acute STEMI occur and what is the treatment for the complication?

Answer 19

1. Occur 3-5 days post MI

2. Tx: IABP (balloon) followed by invasive surgery

Question 20

When do tachyarrhythmia complications occur from MI and what is the treatment?

Answer 20

Ventricular: occur within 48hrs of acute MI
Atrial: unstable - electrocardio conversion
stable - beta blocker/digoxin + anticoagulant

Question 21

Treatment for bradyarrhythmia complication of MI.

Answer 21

1. Observation
2. Atropine
3. Pacemaker (temp or permanent)