Myocardial Infarction (STEMI & Non-STEMI)

Question 1

Most MIs are caused by atherosclerosis; what are some other causes?

Answer 1

Vasospasm
Vasculitis
Dissection
Genetics

Question 2

PE findings in AMI

Answer 2

May be normal

S4 gallop

BP is variable — in general, anterior MI is high catecholamine state meaning increased HR and BP are likely. In inferior MI, more likely to see bradycardia and decreased BP because of possible ischemia to SA and AV nodes

Heart failure possible — S3, crackles, JVD, new murmur

Question 3

Define STEMI in terms of ECG findings in men vs. women

Answer 3

Men: ST elevation of 2+ mm at J point in V2-V3

Women: ST elevation 1.5+ mm in absence of LVH; or 1+ mm in at least 2 contiguous chest or limb leads

Another possible finding = New LBBB (proximal LAD injury —> anterior infarct) — LBBB may obscure ST elevation analysis

Question 4

In the early acute phase of MI, there is an increase in amplitude of the ___ wave and _____ upward ST pattern

Answer 4

T; convex

Question 5

Causes of ST segment elevation other than AMI

Answer 5

Pericarditis

LVH with J point elevation

Noraml variant early repolarization

Question 6

Resolution of ST elevation is variable — roughly 2 weeks for inferior wall; later anterior wall.

Persistent ST elevation beyond 2 weeks is suggestive of possible _____ _____

Answer 6

Ventricular aneurysm (could also be persistent wall motion abnormalities as well)

Question 7

1-2 mm, narrow, small Q waves are normal (non-pathologic) in what leads?

Answer 7

1, aVL, aVF, V5, V6

Question 8

The ST segment is normally isoelectric. Sometimes it can be normally elevated, but not more than 1 mm in ______ leads and 2 mm in ______ leads

It is never normally depressed more than ____ mm.

Answer 8

Standard; chest

0.5

Question 9

Normal T wave direction in all leads

Answer 9

Upright in 1, 2, V3-6

Inverted in aVR

Variable in 3, aVL, aVF, V1-V2

Question 10

In terms of height, the T wave should not be greater than _____ in standard leads, and not greater than _____ in precordial leads

Answer 10

5 mm; 10 mm

Question 11

What parts of the ECG are associated with myocardial ischemia vs. myocardial injury vs. myocardial infarct?

Answer 11

Ischemia = T wave inversion or tall, peaked T waves

Injury = ST elevation

Necrosis or infarct = Q wave or QS complex

Question 12

What pathologic ECG pattern remains forever after MI occurs?

Answer 12

Q waves

Question 13

Significant ___ waves and T wave _______ in leads II, III, and aVF are seen with inferior infarct. With ______ damage, changes may also be seen in V5 and V6

Answer 13

Q; inversion; lateral

Question 14

ECG changes seen with posterior infarct

Answer 14

Since no ECG lead reflects posterior electrical forces, changes are reciprocal of those in anterior leads.

Lead V1 shows unusually large R wave (reciprocal of posterior Q wave) and upright T wave (reciprocal of posterior T wave inversion)

Question 15

Lab findings in STEMI

Answer 15

Increased WBC 12,000-15,000 (hours to 2-4 days)

Increased CRP

BNP - increased ventricular wall stress and fluid overload

Cardiac biomarkers — troponin I or T detectable 1-4 hours after onset AMI and peak at 10-24 hrs; persist for 5-14 days

Question 16

_____ _____ can cause false positive cTnT

Answer 16

Renal failure

Question 17

What are non-myocardial infarction causes of elevated troponin level?

Answer 17

Cardiac: cardiac contusion, surgery, ablation, shocks, myocarditis, pericarditis, heart failure, cardiomyopathy, aortic dissection, severe aortic stenosis, tachycardia’s

Pulmonary: PE, pulmonary HTN, respiratory failure

Neurologic: stroke, intracranial hemorrhage

Other: shock, renal failure

Question 18

ED standard of care in STEMI

Answer 18

12 lead ECG with continuous cardiac monitoring

IV lines inserted

Cardiac enzymes (cTnI), CBC, CMP, PT, PTT

Question 19

Choices for reperfusion strategy

Answer 19

Primary percutaneous coronary intervention (PCI) with angioplasty and stenting (must get to cath lab within 90 minutes) — this is preferred choice for STEMI sx <12 hours

Fibrinolysis — fibrinolytic or thrombolytic; begin in ED within 30 mins (if unable to do PCI for any reason)

If patient needs PCI and hospital does not have capability, pt must be transferred within 120 minutes

Question 20

Compared to fibrinolysis, reperfusion therapy has lower risk of _____ and ______

Answer 20

Death; intracranial hemorrhage

Question 21

Contraindications to fibrinolytic therapy

Answer 21

Absolute:
Active bleeding
Prior hemorrhagic stroke
Ischemic stroke w/i 3 months
Intracranial or spinal cord neoplasm
AV malformation
Suspected aortic dissection
Closed head or facial trauma w/i 3 months

Relative:
Severe uncontrolled HTN
Anticoagulation with INR >2-3
Recent major trauma or surgery
Prolonged CPR (>10 mins)
Active peptic ulcer
Recent noncompressible vascular punctures
Pregnancy
Prior exposure or allergic reaction to streptokinase/anistreplase

Question 22

Pharmacologic management of STEMI

Answer 22

ASA given on presentation unless contraindicated

IV heparin or Enoxaparin

Antiplatelet agent (clopidogrel, prasugrel, ticagrelor)

Nitroglycerin to relieve vasoconstriction, relieve pain, and reduce pre/afterload

Morphine for pain

Beta blocker (especially if increased BP or HR) — DONT use in decompensated HF, decreased HR, decreased BP, MCO2

Oxygen

Stool softener

ACEI (helpful if EF decreased or increased BP; prevent remodeling with statin)

Question 23

What medications are used for 1 year after PCI for STEMI with stenting to prevent stent stenosis?

Answer 23

Dual antiplatelet therapy = ASA and clopidogrel/prasugrel/ticagrelor

Question 24

A pt presenting 2-10 weeks after MI with chest pain different from their MI, dyspnea, and pain/sx improves with leaning forward is likely _______ syndrome. It is treated with ____

Answer 24

Dressler; ASA, NSAID

Question 25

Complications of MI

Answer 25

Recurrent chest pain
Acute pericarditis (Dressler syndrome)
Arrhythmias (Vtach, Vfib, Afib, sinus bradycardia)
Second degree AV block (Wenckebach)
Heart failure
Mitral valve regurg
VSD
Thromboembolism

Question 26

Benign complication of MI in which there is ventricular tachycardia (60-100 bpm) noted after fibrinolytic therapy is begun

Answer 26

Accelerated idioventricular rhythm (AIVR)

Question 27

Sinus bradycardia is a complication associated with _____MI

Answer 27

Inferior

Question 28

Second degree AV block (Wenckebach) is most frequently associated with _____ MI

Answer 28

Inferior

Question 29

RV infarct may occur as a complication in 10-15% of _______ STEMI. On PE, lungs may be clear and BP is decreased. ______ sign may be noted in which there is distention of jugular vein on inspiration. These patients should be treated with ______

Answer 29

Inferior; Kussmaul; IV fluids

Question 30

A septal rupture with VSD is associated with _____ MI

Answer 30

Anterior wall

Question 31

LV free wall rupture causes ______ and is usually fatal

Answer 31

Cardiac tamponade

Question 32

LV aneurysm is a complication associated with _____ MI

Answer 32

Anterior

Question 33

What changes can be seen on echocardiogram post-MI?

Answer 33

Global and regional wall motion abnormalities
Murmur
Papillary muscle dysfunction/rupture
VSD
LV free wall rupture
LV aneurysm
Mural thrombosis