Cardiovascular: Myocardial Infarction

Question 1

what is a MI?

Answer 1

ecrosis of myocardial tissue following occlusion of a coronary artery and subsequentischaemia

Question 2

what is the most common cause of a MI?

Answer 2

Coronary Heart Disease (atheromatous plaque)

Question 3

what is a STEMI?

Answer 3

ST-segment elevation myocardial infarction, which is generally caused by complete and persisting blockage of the artery.

Question 4

what causes a STEMI?

Answer 4

complete and persisting blockage of the artery

Question 5

what is a NSTEMI?

Answer 5

Non-ST-segment elevation myocardial infarction, reflecting partial or intermittent blockage of the artery.

Question 6

what causes a NSTEMI?

Answer 6

partial or intermittent blockage of the artery

Question 7

what are risk factors for an MI?

Answer 7

Hypertension.
Physical inactivity.
Hypercholesterolemia. 
Diabetes mellitus. 
Family history/personal history of CHD. 
Stress. 
Illicit drug use
Male sex.
Advancing age.
Obesity.
Smoking.

Question 8

what are clinical features of an MI?

Answer 8

• New onset of chest pain at rest: crushing pressure, tightness, pain, or a squeezing or aching sensation in your chest or arms that may spread to your neck, jaw or back.
• Nausea and vomiting.
• Indigestion, heartburn or abdominal pain.
• Shortness of breath.
• Sweating and clamminess.
• Fatigue.
• Lightheadedness or sudden dizziness.
• Feeling of impending doom.

Question 9

how long would chest pain symptoms continue for to be considered an MI and not angina?

Answer 9

20 mins

Question 10

what is a silent MI?

Answer 10

If the patient has no symptoms or atypical symptoms, the MI may be categorised as ‘silent’.

Question 11

which conditions present in a similar way to an MI?

Answer 11

Angina. 
Acute pericarditis. 
Myocarditis. 
Aortic stenosis.
Aortic dissection.
PE.
Pneumonia.

Question 12

what investigations would you do to confirm a diagnosis of a MI?

Answer 12

Bloods

• Troponins
• Creatine-kinase-MB
• Myoglobin

ECG

Question 13

The cardiac Troponin complex is made up of which 3 distant troponin proteins?

Answer 13

I (I inhibits the myosin binding site on the actin)

T (T attaches the complex to tropomyosin)

C (C binds calcium during excitation-contraction coupling)

Question 14

when diagnosing an MI what do you do if the initial troponin assay is negative?

Answer 14

repeat it 6-12 hours after admission

Question 15

when diagnosing an MI what do you do if there is no ST elevation on an ECG?

Answer 15

perform troponin blood tests

Question 16

what is the treatment for a STEMI?

Answer 16

Immediately assess eligibility for coronary reperfusion therapy

deliver either:
- Primary PCI: (if available within 2 hours of presentation).

• Thrombolysis: (if PCI not available within 2 hours).

Question 17

what is the treatment for a NSTEMI?

Answer 17

BATMAN

B – Beta blockers (slows the heart rate + reduces cardiac demand)
A – Aspirin (300mg) FIRST LINE
T – Ticragrelor (or clopidogrel)
M – Morphine
A – Anticoagulant (LMWH (Enoxaparin))
N – Nitrates (GTN) to relieve coronary artery spasm

Question 18

what lifestyle modifications can a patient make post-MI?

Answer 18

• physically active
• stop smoking
• drink in moderation

Question 19

what does post MI drug therapy include?

Answer 19

(6 As)
Aspirin.

A beta-blocker e.g. Atenolol.

ACE inhibitors, e.g. ramipril.
Statins, e.g. atorvastatin.

Antiplatelet: Clopidogrel 75 mg/day for 9–12 months should be added in moderate–high-risk patients with non-ST elevation acute coronary syndrome (NST-ACS)

Aldosterone antagonist – For those with clinical heart failure (eplerenone).