Pharmacology of Acute Coronary Syndrome

Question 1

Describe STEMI?

Answer 1

Complete occlusion of blood vessel lumen resulting in transmural injury and infarct
Reflects in ECG, rise in troponin, and crackles

Question 2

Describe unstable angina

Answer 2

Not predictable or constant
Can be progressive
Plaque and thrombus forms partial occlusion of vessel
Pain at rest

Question 3

Explain NSTEMI?

Answer 3

The plaque rupture and thrombus formation causes partial occlusion to vessel
Results in injury and infarct to the subendocardial myocardium

Question 4

Describe stable angina?

Answer 4

Increased demand in the setting of stable atheroma plaque
Vessel unable to dilate enough to allow adequate blood flow to meet demand

Question 5

What are the goals of therapy for NSTEMI and unstable angina?

Answer 5

Increase myocardial O2 supply - vasodilation, stop platelet aggregation and correct hypoxaemia
Decrease myocardial O2 demand - reduce HR, BP, preload and contractibility
Overall, reduce ischaemic insult

Question 6

What is initial management of NSTEMI and unstable angina?

Answer 6

M - Morphine
O - Oxygen
N - Nitrates
A - Aspirin
C/T/P - Clopidogrel/ Ticagrelor/ Prasugrel

Question 7

What is used to decrease myocardial oxygen demand for NSTEMI and unstable angina?

Answer 7

Bisoprolol - beta blocker
Nitrates
Ramipril - ACE inhibitor
Atorvastatin - stabilises plaque

Question 8

What are 3 key antiplatelet agents?

Answer 8

Aspirin
Clopidogrel/ Ticagrelor/ Prasugrel
Fondaparinux

Question 9

Explain aspirin’s mechanism

Answer 9

Thromboxane A2 inhibitor
Inhibit platelet activation and recruitment

Question 10

Explain Clopidogrel’s mechanism

Answer 10

Inhibits ADP activation of P2Y12 receptor

Question 11

Explain Fondaparinux’s mechanism?

Answer 11

Synthetic Pentasaccharide
Decreases the conversion of prothrombin to thrombin by also decreasing the conversion of fibrinogen to fibrin
Means less clots

Question 12

What are the goals for therapy for STEMI?

Answer 12

Unblock the artery
Emergency angioplasty and if that not available then use thrombolytic
Can stop platelet aggravation

Question 13

What imagery can be used?

Answer 13

ECHO
CT coronary angiogram
Angiogram

Question 14

How does thrombolysis work?

Answer 14

Recombinant tissue plasminogen activator (rtPA)
Converts plasminogen to plasmin and plasmin lyses clots as breaks does fibrinogen and fibrin within clot

Question 15

What are fibrin specific agents?

Answer 15

All catalyse conversion of plasminogen to plasmin in absence of fibrin

Question 16

What are fibrin specific agents used for thrombolysis?

Answer 16

Alteplase
Tenecteplase - higher fibrin specificity

Question 17

What are non-fibrin specific agents?

Answer 17

Catalyse systemic fibrinolysis
Ex. Streptokinase - lower bleeding risk

Question 18

What are some contraindications for thrombolysis?

Answer 18

Prior intracranial haemorrhage, intracranial lesion, ischaemic stroke within 3 months, aortic dissection, active bleeding and significant closed head trauma

Question 19

What are the benefits for thrombolysis?

Answer 19

Reduction in morality and more when used with aspirin
Smoker paradox - more benefit

Question 20

What are the principles for treatment?

Answer 20

Reduce myocardial workload, improve coronary artery perfusion, prevent myocardial damage and unblock the artery