Acute Coronary Syndrome Flashcards
What conditions are included under the term ‘Acute Coronary Syndrome’?
Unstable angina
S-T elevation MI (STEMI)
Non-S-T elevation MI (NSTEMI)
What might you see in the troponin results of a patient with each of these conditions:
- Unstable angina
- Non-S-T elevation myocardial infarction
- S-T elevation myocardial infarction
- UA: Troponin normal
- NSTEMI: Troponin rises
- 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.
What might you see on an ECG of a patient with each of these conditions:
- Unstable angina
- Non-S-T elevation myocardial infarction
- S-T elevation myocardial infarction
- UA: Normal
- NSTEMI: ST-depression, T-wave inversion or normal
3: STEMI: ST-elevation, new LBBB
Which ECG leads give an anterior view?
V3, V4
Which ECG leads give an anterolateral view?
V3-V6
Which ECG leads give an anteroseptal view?
V1-V4
Which ECG leads give a septal view?
V1, V2
Which ECG leads give a lateral view?
V5, V6, I, aVL
aVL = L = lateral
Which ECG leads give an inferior view?
II, III, aVF
aVF = F = foot
Why is lead II used as the rhythm strip?
The view follows the same plane as the heart’s electrical conduction.
What is the aetiology of acute coronary syndromes?
Primarily thrombus formation due to atherosclerotic disease.
Other rarer causes include:
- Emboli
- Coronary spasm (Prinzmetal’s angina or cocaine use)
- Vasculitis
Which coronary vessel is likely to be occluded if there are ischaemic ECG changes in leads V1-V4?
Left anterior descending artery.
These leads view the anterior wall (V3-V4) and septum (V1-V2); both are usually supplied by the LAD.
Which coronary vessel is likely to be occluded if there are ischaemic ECG changes in leads I, aVL, V5, V6?
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.
Which coronary vessel is likely to be occluded if there are ischaemic ECG changes in leads II, III, aVF?
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.
Risk factors for acute coronary syndromes?
Older age
Male
Family history
Smoking
Cocaine use
Diabetes
Hypertension
Hyperlipidaemia
Obesity
Sedentary lifestyle
Typical symptoms on presentation of acute coronary syndrome?
Acute central chest pain, not relieved by rest.
Pain may radiate to shoulder, arm or jaw.
Nausea, sweating, shortness of breath, palpitations.
What signs might you find on examination of patient with acute coronary syndrome?
Anxiety, pallor, sweaty (clammy)
Brady- or tachycardic
BP ↑ or ↓
Investigations if acute coronary syndrome is suspected?
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
Management of acute coronary syndrome?
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)
What are the indications for a Coronary Artery Bypass Graft (CABG)?
Indications for CABG:
- Unable to perform PCI (diffuse disease)
- Left main coronary artery disease
- Triple-vessel disease
- Depressed ventricular function
Case history 1 for unstable angina
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.
Case history 2 for unstable angina
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.
Case history for non-ST-elevation myocardial infarction (NSTEMI)
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.
Case history 1 for ST-elevation myocardial infarction
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.
