Acute Coronary Syndrome

Question 1

What conditions are included under the term ‘Acute Coronary Syndrome’?

Answer 1

Unstable angina

S-T elevation MI (STEMI)

Non-S-T elevation MI (NSTEMI)

Question 2

What might you see in the troponin results of a patient with each of these conditions:

1. Unstable angina
2. Non-S-T elevation myocardial infarction
3. S-T elevation myocardial infarction

Answer 2

1. UA: Troponin normal
2. NSTEMI: Troponin rises
3. STEMI: Troponin rises

Serum troponin levels will rise in response to ischaemia of the cardiac muscles. In unstable angina, perfusion is transiently reduced but not sufficiently for ischaemia to develop. By definition, MI occurs when perfusion is reduced (NSTEMI) or nil (STEMI) and this damaged myocardium will release troponin.

Question 3

What might you see on an ECG of a patient with each of these conditions:

1. Unstable angina
2. Non-S-T elevation myocardial infarction
3. S-T elevation myocardial infarction

Answer 3

1. UA: Normal
2. NSTEMI: ST-depression, T-wave inversion or normal
   3: STEMI: ST-elevation, new LBBB

Question 4

Which ECG leads give an anterior view?

Answer 4

V3, V4

Question 5

Which ECG leads give an anterolateral view?

Answer 5

V3-V6

Question 6

Which ECG leads give an anteroseptal view?

Answer 6

V1-V4

Question 7

Which ECG leads give a septal view?

Answer 7

V1, V2

Question 8

Which ECG leads give a lateral view?

Answer 8

V5, V6, I, aVL

aVL = L = lateral

Question 9

Which ECG leads give an inferior view?

Answer 9

II, III, aVF

aVF = F = foot

Question 10

Why is lead II used as the rhythm strip?

Answer 10

The view follows the same plane as the heart’s electrical conduction.

Question 11

What is the aetiology of acute coronary syndromes?

Answer 11

Primarily thrombus formation due to atherosclerotic disease.

Other rarer causes include:

• Emboli
• Coronary spasm (Prinzmetal’s angina or cocaine use)
• Vasculitis

Question 12

Which coronary vessel is likely to be occluded if there are ischaemic ECG changes in leads V1-V4?

Answer 12

Left anterior descending artery.

These leads view the anterior wall (V3-V4) and septum (V1-V2); both are usually supplied by the LAD.

Question 13

Which coronary vessel is likely to be occluded if there are ischaemic ECG changes in leads I, aVL, V5, V6?

Answer 13

Circumflex artery.

The circumflex artery supplies the lateral aspect of the heart (wall of the left ventricle) and leads I, aVL, V5, V6 look at this region.

Question 14

Which coronary vessel is likely to be occluded if there are ischaemic ECG changes in leads II, III, aVF?

Answer 14

Right coronary artery.

This artery usually travels down to the apex of the heart, supplying the inferior aspect. This region is viewed in leads II, III, and aVF.

Question 15

Risk factors for acute coronary syndromes?

Answer 15

Older age

Male

Family history

Smoking

Cocaine use

Diabetes

Hypertension

Hyperlipidaemia

Obesity

Sedentary lifestyle

Question 16

Typical symptoms on presentation of acute coronary syndrome?

Answer 16

Acute central chest pain, not relieved by rest.

Pain may radiate to shoulder, arm or jaw.

Nausea, sweating, shortness of breath, palpitations.

Question 17

What signs might you find on examination of patient with acute coronary syndrome?

Answer 17

Anxiety, pallor, sweaty (clammy)

Brady- or tachycardic

BP ↑ or ↓

Question 18

Investigations if acute coronary syndrome is suspected?

Answer 18

12-lead ECG:

• STEMI: ST elevation, new LBBB, hyperacute or inverted T waves.
• NSTEMI: ST depression, T-wave inversion, or normal.
• UA: Often normal/non-specific changes

Cardiac enzymes:
- Troponins

Question 19

Management of acute coronary syndrome?

Answer 19

STEMI (inc. new LBBB): Urgent revascularization required = PCI

NSTEMI/UA: MONA

• Morphine PRN
• Oxygen IF SATS < 94 ONLY
• Nitrates
• Antiplatelets/anticoagulants

Antiplatelets: [dual therapy] aspirin + clopidogrel or ticagrelor for at least 12 months

Anticoagulants: e.g. Fondaparinux 3 days or per guidelines

B-blocker, ACEi

Statin

Cardiac rehab (e.g. smoking cessation, diet control)

Question 20

What are the indications for a Coronary Artery Bypass Graft (CABG)?

Answer 20

Indications for CABG:

• Unable to perform PCI (diffuse disease)
• Left main coronary artery disease
• Triple-vessel disease
• Depressed ventricular function

Question 21

Case history 1 for unstable angina

Answer 21

A 65-year-old man, who smokes and has a history of hypertension and peripheral vascular disease, now presents with increasing frequency and severity of chest discomfort over the past week. He reports that he previously had chest pain after walking 100 metres, but now is unable to walk more than 50 m without developing symptoms. The pain radiates to the left side of the neck and is only eased after increasing periods of rest.

Question 22

Case history 2 for unstable angina

Answer 22

A 45-year-old woman, with a history of type 1 diabetes diagnosed when she was a teenager, presents to the accident and emergency department complaining of abdominal pain, nausea, and shortness of breath that woke her up from sleep.

Question 23

Case history for non-ST-elevation myocardial infarction (NSTEMI)

Answer 23

A 69-year-old man develops worsening substernal chest pressure after shovelling snow in the morning before work. He tells his wife he feels a squeezing pain that is radiating to his jaw and left shoulder. He appears anxious and his wife calls for an ambulance, as he is distressed and sweating profusely. Past medical history is significant for HTN and he has been told by his doctor that he has borderline diabetes. On examination in the emergency department he is very anxious and diaphoretic. His heart rate is 112 bpm and BP is 159/93 mmHg. The ECG is significant for ST depression in the anterior leads. Three doses of sublingual glyceryl trinitrate provide little relief.

Question 24

Case history 1 for ST-elevation myocardial infarction

Answer 24

A 54-year-old man with a medical history of hypertension, diabetes, dyslipidaemia, smoking, and family history of premature coronary artery disease presents with retrosternal crushing chest pain (10/10 in intensity), radiating down the left arm and left side of the neck. He feels nauseated and light-headed and is short of breath. Examination reveals a hypotensive, diaphoretic man in considerable discomfort with diffuse bilateral rales on chest auscultation. ECG reveals convex ST-segment elevation in leads V1 to V6.

Question 25

Case history 2 for ST-elevation myocardial infarction

Answer 25

A 70-year-old woman is 2 days post-operative for knee replacement surgery. Her past medical history includes type 2 diabetes and a 40 pack-year history of smoking. She reports feeling suddenly unwell with dizziness, nausea, and vomiting. She denies any chest pain. On examination she is hypotensive and diaphoretic. ECG shows convex ST-segment elevation in leads II, III, and aVF with reciprocal ST segment depression and T-wave inversion in leads I and aVL.

Question 26

What is a silent MI and which demographic is usually affected?

Answer 26

ACS without chest pain, mostly seen in elderly and diabetic patients.

May present with: syncope, pulmonary oedema, epigastric pain and vomiting, post-operative hypotension or oliguria, acute confusional state, stroke, and diabetic hyperglycaemic states.