Myocardial Infarction

Question 1

What is a myocardial infarction?

Answer 1

A heart attack

When a blockage stops blood flow through the coronary arteries of the heart, meaning that the heart muscles are starved of oxygen and eventually die.

Question 2

Three types of ACS. What are the differences between them?

Answer 2

Unstable angina: no trop raise, no ECG changes

NSTEMI: trop raise, can have ECG changes but no ST elevation

STEMI: trop raise, ECG changes ST elevation

Question 3

What are the symptoms of an MI?

Answer 3

Cardiac chest pain:

• gradual onset
• unremitting
• severe (usually)
• occurs at rest
• radiates to left arm, jaw, neck

Breathlessness
N+V
Anxiety
Clammy, sweaty

Question 4

What are the signs of an MI?

Answer 4

Sweating
Tachy or bradycardia
Tachypnoea
Hyper or hypotension

Signs of heart failure (displaced apex, pulmonary and peripheral oedema)

Signs of hyperlipidaemia: xanthalasma on eyes, xanthoma on tendons, corneal arcus

Bruits
Arrhythmias
Extra heart sounds S3, S4

Question 5

What are the causes of MI?

Answer 5

Rupture of an atherosclerotic plaque that leads to formation of thrombus

Coronary vasospasm
Drug abuse
Dissection of coronary artery (Marfan’s?)

Question 6

What are the risk factors for MI?

Answer 6

Male gender
Age
Family history of CHD
Hyperlipidaemia
Diabetes
Renal failure
L ventricular systolic dysfunction
Smoking
High cholesterol
Obesity
Sedentary lifestyle
Stress

Question 7

What is the initial management of a patient with a suspected MI?

Answer 7

ECG to see if STEMI or NSTEMI

MONA BC
Morphine
Oxygen (only if hypoxic)
Nitrate (GTN spray)
Aspirin 300mg
Beta blockers
Clopidogrel or other antiplatelet (ticagrelor 180mg)

If STEMI, eligible and within time frame - PCI
If not within timeframe: fibrinolysis with alteplase or streptokinase

If NSTEMI monitor closely, ?fibrinolysis

Question 8

What is troponin?

Answer 8

Cardiac enzyme

Integral to muscle contraction in skeletal & cardiac muscle

Question 9

What do raised troponin levels mean?

Answer 9

Cardiac muscle cell death

Troponin is released into the blood upon cardiac injury

Question 10

Ideally, in what time period should someone with an MI have PCI?

Answer 10

Within 120 mins of first medical contact

Question 11

What is fibrinolysis?

Answer 11

Breaking down the clot

Fibrinolytic drugs:
Streptokinase, ateplase

Drugs that break down the clot

Question 12

Ideally, in what time period should someone with an MI receive fibrinolytic drugs?

Answer 12

Within 30 mins of admission

Question 13

Do raised troponin levels definitely confirm an MI?

Answer 13

No!
Troponin can be raised for other reasons:
Gram -ve sepsis
Myocarditis
Heart failure

Question 14

What tests should be done in a suspected MI?

Answer 14

ECG

Bloods:
FBC, U+E, glucose, lipids, troponin

CXR: look for cardiomegaly
ECHO
Angiogram

Question 15

What is the subsequent management of MI patients? After the acute event is over.

Answer 15

Bed rest with continuous ECG monitoring

Thromboembolism prophylaxis (LMWH) until fully mobile

Prescriptions to take home:

• Aspirin
• Anti-platelet (clopidogrel, ticagrelor)
• B-blockers
• ACEi
• Statin

Modify lifestyle