Acute Coronary Syndrome

Question 1

What are the common characteristics of ischaemic chest pain?

Answer 1

Central chest pain that can radiate to the inner left arm, neck or abdomen
Often described as ‘crushing’ or ‘band-like’
Generally remits in several minutes and can be relieved by rest of a sublingual nitrate (GTN)
Often exacerbated by exercise, effort, stress of tachycardia

Question 2

What non-cardiac conditions are differentials for cardiac pain?

Answer 2

Musculoskeletal (e.g. costochondritis) - usually localised and reproducible on palpation or movement
Reflux oesophagitis - often accompanied with dysphagia or pain on swallowing, nausea and is not exacerbated by effort
Gastritis - epigastric, modified by eating, antacids
Pericarditis - sharp, relieved when sitting, ECG changes
Mediastinitis - raised inflammatory markers, constant pain, septic

Question 3

What signs may be present on examination of someone with cardiac ischaemia?

Answer 3

Tachycardia
Pallor
Hypotension 
Dyspnoea 
Cyanosis 
Low SpO2 
Bibasal crackles
Mitral regurgitation 
Atrial fibrillation 
Raised JVP 
Oedema 
Hepatomegaly

Question 4

What is the difference between stable and unstable angina?

Answer 4

Stable angina is exacerbated by exertion, pain is relieved when resting
Unstable angina can occur at any time (and is therefore classed as an acute coronary syndrome)

Question 5

What is unstable angina?

Answer 5

Condition in which your heart is not receiving enough blood/ oxygen (poor blood flow usually due to a non-occlusive thrombus)

Question 6

What clinical findings would you expect in someone with unstable angina?

Answer 6

Prolonged (>20 mins) pain at rest or on minimal exertion

Question 7

How do you differentiate between unstable angina and an NSTEMI?

Answer 7

Troponin levels would be raised in NSTEMI (by 6 hour of symptoms commencing) but not in unstable angina

[Normal troponin levels are <0.4]

Question 8

What ECG changes might you see in someone with unstable angina or an NSTEMI?

Answer 8

Inverted T waves

ST depression

Question 9

What is an NSTEMI?

Answer 9

Non-ST elevated myocardial infarction - acute ischaemic event causing mild myocyte necrosis usually due to a non-occlusive thrombus sufficient to cause tissue damage

Question 10

What is a STEMI?

Answer 10

ST elevated myocardial infarction - complete thrombus occlusion of a blood vessel supplying the heart (can be a coronary artery or a smaller branch) causing the muscle supplied by this vessel to die

Question 11

What ECG changes will you see in a STEMI?

Answer 11

ST elevation in 2+ anatomically contiguous leads (>1mm)

Question 12

What non-cardiac conditions can cause raised Troponin?

Answer 12

Renal failure

Question 13

What are the possible complications of acute coronary syndrome?

Answer 13

Hypotension 
Cardiogenic shock 
AKI 
Arrhythmias 
Papillary muscle rupture 
Pericarditis 
Dressler's Syndrome

Question 14

What are the phases of myocardial infarction?

Answer 14

Ischaemic phase (cells able to survive on anaerobic metabolism initially)
Infarction phase (irreversible damage occurs as anaerobic metabolism becomes unable to keep up with cell needs)

Question 15

How do ECG changes differ between ischaemia, injury and infarction (or scar)?

Answer 15

Ischaemia = T wave inversion, ST depression
Injury = ST elevation
Infarction/ scar = pathological Q wave formation

Question 16

What is the initial management of unstable angina or an NSTEMI?

Answer 16

Hypoxia, pulmonary oedema or continuing ischaemia = oxygen
Pain relief = nitrates (e.g. GTN) - vasodilation and relaxation of smooth muscle cells, morphine (IV)
Antiplatelet/ anticoagulants = aspirin, clopidogrel (inhibits platelet aggregation), heparin (anti-coagulant)
Ongoing management = beta-blockers (e.g. Bisoprolol)

Question 17

What primary and secondary prevention strategies can be used in management of ACS?

Answer 17

Lower cholesterol = diet, statins (Atorvastatin, Simvastatin)
Antiplatelets/ anticoagulants = Aspirin, Clopidogrel
Reduce work of heart = Beta-blockers (Bisoprolol, Atenolol, Propanolol), ACE inhibitors (Ramipril)
Exercise
Smoking cessation

Question 18

What are the main principles of managing acute coronary syndromes?

Answer 18

1. Prevention
2. Immediate care
3. Manage complications
4. Cardiac rehabilitation, palliative care, transplant

Question 19

What are the diagnostic steps when patient has symptoms of an ACS?

Answer 19

1. Admission (e.g. presents with chest pain)
2. Working diagnosis (history)
3. ECG (normal, ischaemia, injury)
4. Biochemistry (?raised troponin)
5. Diagnos (STEMI, NSTEMI, unstable angina)

Question 20

What is the basic pathophysiology of ischaemic heart disease?

Answer 20

Normally a result of atherosclerotic plaque in coronary arteries (this can result in a fixed obstruction and lead to chronic ischaemic heart disease) - plaque can rupture exposing factors (e.g. vWF and collagen) that result in a clot formation further narrowing lumen which can cause a STEMI (full occlusion) or an NSTEMI/ unstable angina (partial occlusion) due to lack of oxygen supply to the heart muscles