Acute Coronary Syndrome/Myocardial Infarction

Question 1

What 3 things does ACS include?

Answer 1

1. STEMI
2. NSTEMI
3. unstable angina

Question 2

How is unstable angina different to stable angina?

Answer 2

• increasing severity
• recent onset
• unpredictable
• occurs at rest (unlike stable angina)
• may be previous deterioriation of stable angina

Question 3

What are clinical features of unstable angina?

Answer 3

• chest pain daily/several times per day
• increasing severity of chest pain
• retrosternal chest pain radiating to jaw, arm, neck
• sweating
• nausea
• tachycardia
• dyspnoea
• 4th heart sound
• carotid bruit

Question 4

What are the symptoms of an acute STEMI?

Answer 4

• acute central chest pain (can last for hours)
• pain radiating to arms, neck, jaw, back + epigastrium
• dyspnoea
• nausea/vomiting
• sweating
• restlessness
• palpitations
• 20% of pts have no pain (silent) eg. elderly, diabetics or post-transplant pts - this goes unnoticed or may be present with hypotension, syncope, arrhythmias, pulm oedema, epigastric pain, acute confusion, stroke

Question 5

What are signs of an acute STEMI?

Answer 5

may present with no physical signs unless complications develop athough patient often appears:

• anxious
• pale
• grey
• inc BP
• signs of HF

Question 6

What investigations are done for STEMI?

Answer 6

• bloods - FBC, U+Es, glucose, lipids
• ECG
• cardiac markers - troponin, CK, AST + LDH
• CXR -> cardiomegaly, pulm oedema, wide mediastinum
• coronary angiogram -> thrombus present w/ occlusion

Question 7

What might happen in an ECG days later following an MI?

Answer 7

• ST segment usually returns to normal
• T wave may return to upright
• however, Q wave remains - sign of prev MI

Question 8

What ECG leads give rise to what kind of MIs? Also give the blood vessels involved

Answer 8

Question 9

Necrotic cardiac muscle releases several enzymes and proteins into the systemic circulation.

When are these measured and what do these include?

Answer 9

• done at 0h, 6h and 12h after admission
• troponin T + I - regulatory proteins, highly specific + sensitive for cardiac muscle damage (myocardial necrosis), serum levels inc within 3-12h from onset of chest pain, peak at 24-48h and return to baseline over 5-14days
• CK - also produced by sk muscle + brain, is less sensitive than troponin. CK-MB however is specific for heart muscle damage, it’s a myocardial-bound isoenzyme fraction of CK + the size of enzyme rise is broadly proportional to infarct size. Serum levels inc within 3-12hrs from onset of chest pain, reaches peak values within 24hr and returns to baseline over 2-3 days

For a further episode of chest pain >3 days after first episode, CK-MB is the most useful marker. Troponin levels will remain elevated since first episode and won’t provide info regarding a new episode.

Question 10

What is the diagnostic criteria for an acute MI?

Answer 10

Rise + fall of serum cardiac biomarkers such as troponin and CK-MB, accompanied w/ at least one of the following:

• symptoms of ischaemia
• ECG changes of new ischaemia (ST/T changes or new LBBB)
• development of pathological Q waves
• coronary artery intervention
• imaging evidence of new loss of viable myocardium

Question 11

What is the immediate management of a pt having an acute myocardial infarction?

Answer 11

• ABCDE!
• oxygen 2-4L, aim for SaO₂ >94% (unless COPD pt)
• brief history + exam, 12-lead ECG, BP, bloods (cardiac enzymes, FBC etc)
• aspirin 300mg PO unless already given OR clopidogrel 300mg PO
• morphine 5-10mg IV + antiemetic eg. metaclopramide 10mg IV
• GTN sublingually 2puffs or 1 tablet PRN
• reperfusion: primary PCI or thrombolysis w/ dalteparin for 24-48hr (LMWH/UFH)
• beta blocker eg. atenolol 5mg IV (unless asthma or LVF)
• high intensity statin

MENUMONIC: MONARCH (morph, o2, nitrates, aspirin, reperfusion, clopidogrel, heparin)

Question 12

The time frame for door-to-needle thrombolytic administration should be within 30 mins, whereas the door-to-balloon PCI time should be less than 90 minutes.

What are contraindication for thrombolysis?

Answer 12

• ABSOLUTE:
  
  • any active bleeding from any site within body
  • any recent history of haemorrhagic stroke
  • pregnancy
  • taking warfarin
• RELATIVE:
  
  • active liver disease
  • peptic ulcer disease

Question 13

What is the long-term management for STEMI?

Answer 13

1. education + lifestyle advice
2. beta-blocker, atenolol 5mg unless CI
3. atorvastatin
4. ACEi
5. dual antiplatelet therapy for 1 yr - clopidogrel 300mg
6. aspirin

Question 14

What is the specific management for NSTEMI?

Answer 14

1. beta-blocker, atenolol 5mg unless contraindications
2. LMWH
3. IV nitrates
4. consider for coronary angiography and PCI
5. grace score
6. assess for low risk or high risk and treat appropriately:

LOW-RISK (no further pain, flat or inverted T or normal ECG + negative troponin) -> maybe discharge if repeat troponin is negative after 12hr

HIGH-RISK (persistent or recurrent ischaemia, ST dep, diabetes, inc troponin) -> infusion of glycoprotein 2b/3a antagonist + clopidogrel

Question 15

What factors to assess and intervene on are important to touch up on post-MI, in a primary care setting?

Answer 15

• Assessment of:
  
  • attitude + psychological state
  • exercise + abilities and propensities
  • dietary habits + knowledge
  • smoking habits
  • blood pressure
  • full lipid profile (cholesterol will be lower than usual for 6weeks post MI)
• Intervention:
  
  • cardiac rehab
  • stop smoking (record smoking status + advice)
  • dietary advice w/ weight control if indicated
  • control BP - tx threshold is 140/90

Question 16

What are complications of MI?

Answer 16

• pericarditis
• ventricular aneurysm
• dressler’s syndrome
• arrhythmia
• heart block
• heart failure
• mural thrombosis
• thromboembolism
• rupture of free wall of infarcted ventricle

Question 17

When do you give PCI for reperfusion in STEMI?

Answer 17

if:

• within 12hr symptom onset
• available within 120 mins