Acute coronary syndromes

Question 1

What does term acute coronary syndromes mean?

Answer 1

This term covers a spectrum of acute cardiac conditions from unstable angina to varying degrees of evolving myocardial infarction (MI)

Question 2

What does the spectrum range from (least to most damage to myocardium)

Answer 2

• Unstable angina (No ECG changes)
• Non- Q wave MI (Non-ST-elevation MI)
• Q wave MI (ST elevation MI)

Question 3

What is the clinical classification of unstable angina?

Answer 3

• Cardiac chest pain at rest
• Cardiac chest pain with crescendo pattern
• New onset angina

Question 4

How would you diagnose unstable angina?

Answer 4

• history
• ECG
• troponin (no significant rise in unstable angina)

Question 5

How is ST-elevation MI diagnosed?

Answer 5

can usually be diagnosed on ECG at presentation

Question 6

How is non-ST-elevation MI diagnosed?

Answer 6

a retrospective diagnosis made after troponin results and sometimes other investigation results are available

Question 7

What is the J point on ECG?

Answer 7

J point is point of inflection

Question 8

When is there is a pathological Q wave?

Answer 8

When there is no R wave

Question 9

What can MI be defined as retrospectively?

Answer 9

non-Q wave or Q-wave MI on the basis of whether new pathological Q waves develop on the ECG as a result of it

Question 10

What is ST elevation MI and MI associated with left bundle branch block (LBBB) associated with?

Answer 10

larger infarcts unless effectively treated (and therefore more likely to lead to pathological Q wave formation, heart failure or death)

Question 11

Which type of MI is there a pathological Q wave in?

Answer 11

Q wave MI
- Loss of R wave

Question 12

Describe features of cardiac chest pain in MI

Answer 12

• unremitting
• usually severe but may be mild or absent
• occurs at rest
• associated with sweating, breathlessness, nausea and/or vomiting
• one third occur in bed at night

Question 13

What is the consequence of MIs?

Answer 13

Usually causes permanent heart muscle damage although this may not be detectable in small MIs

Question 14

What are some risk factors of MI?

Answer 14

Higher risk associated with higher age, diabetes, renal failure, left ventricular systolic dysfunction etc

Question 15

What is the initial management of MI?

Answer 15

• Get in to hospital quickly – 999 call
• Paramedics – if ST elevation, contact primary PCI centre for transfer for emergency coronary angiography
• Take aspirin 300mg immediately
• Pain relief

Question 16

Describe the hospital management of MI

Answer 16

• Make diagnosis
• Oxygen therapy only if hypoxic
• Pain relief – opiates/ nitrates
• Aspirin +/- platelet P2Y12 inhibitor
• Consider beta-blocker
• Consider other antianginal therapy
• Consider urgent coronary angiography e.g. if troponin elevated or unstable angina refractory to medical therapy

Question 17

What are causes of ACS?

Answer 17

• Rupture of an atherosclerotic plaque and consequent arterial thrombosis is the cause in the majority of cases
• Myocardial infarction due to atherothrombosis is known as ‘type 1’ myocardial infarction
  
  • Most common
• Other causes of myocardial infarction usually fall under the umbrella of ‘type 2’ myocardial infarction

Question 18

What are uncommon causes of ACS?

Answer 18

Uncommon causes include coronary vasospasm without plaque rupture, drug abuse,
dissection of the coronary artery, and thoracic aortic depression
- Type 2 MIs

Question 19

What is troponin?

Answer 19

• A protein complex consisting of troponin C, troponin I and troponin T that regulates actin-myosin contraction
• Highly sensitive markers for cardiac muscle injury
• Not specific for acute coronary syndrome
• May not represent permanent muscle damage

Question 20

Why is troponin not specific for acute coronary syndrome?

Answer 20

• Positive also in:
  
  • Gram-negative sepsis
  • pulmonary embolism
  • myocarditis
  • heart failure
  • tachyarrhythmias
  • cytotoxic drugs
  • vigorous exercise

Question 21

What is an agonist released to activate other platelets?

Answer 21

• ADP
• Target for anti platelet drugs

Question 22

What is the mechanism of aspirin?

Answer 22

Aspirin irreversibly inactivates cyclo-oxygenase 1 so no thromboxane A2

Question 23

Describe features of P2Y12 inhibitors

Answer 23

• Used in combination with aspirin in management of ACS
  
  • Dual anti platelet therapy (DAPT)
• Increase risk of bleeding so need to exclude serious bleeding prior to administration

Question 24

What are 3 oral P2Y12 inhibitors?

Answer 24

clopidogrel, prasugrel and ticagrelor

Question 25

Describe features of anticoagulants

Answer 25

• Used in addition to antiplatelet drugs
• Target formation and/or activity of thrombin
• Inhibit both fibrin formation and platelet activation
• Full-dose anticoagulation used during PCI
• High dose heparin used during cardiopulmonary bypass for CABG surgery

Question 26

What is the main treatment for STEMI?

Answer 26

Primary PCI
- most frequent revascularisation procedure

Question 27

When is coronary angiography usually performed?

Answer 27

for patients with troponin elevation or unstable angina refractory to medical therapy

Question 28

Why do some patients not have obstructive coronary artery disease?

Answer 28

• Actual diagnosis not ACS
• Plaque rupture without significant stenosis and resolution of obstructive thrombus by the time of angiography
• Stress-induced cardiomyopathy without obstructive coronary artery disease

Question 29

What does secondary prevention consist of?

Answer 29

DAPT, high dose statin