Acute Coronary Syndrome (ACS) - STEMI

Question 1

Aetiology of STEMI.

Answer 1

Total Occlusion of a Coronary Artery resulting in Transmural Myocardial Infarction.

Question 2

ECG Changes in STEMI (2).

Answer 2

1. New Left BBB.
2. ST Segment Elevation in Leads Consistent with an Area of Ischaemia.
   2A. ST Segment Elevation >2mm in Adjacent Chest Leads.
   2B. ST Segment Elevation >1mm in Adjacent Limb Leads.

Question 3

Acute Management of STEMI.

Answer 3

If presenting within 12 hours of onset, discuss urgently with local cardiac centre for either :
1. Primary PCI (if available within 2 hours of presentation).
2. Thrombolysis (if PCI is not available within 2 hours).

Question 4

What is Primary PCI? (4)

Answer 4

1. Insertion of a catheter into radial(preferred)/femoral artery and feeding it up into the coronary arteries under X-ray guidance.
2. Use contrast to identify area of blockage.
3. Treat using balloons to widen the gap or devices to remove/aspirate the blockage.
4. Put a stent in to keep the artery open (drug-eluting > bare-metal).

Question 5

What is Thrombolysis? (3)

Answer 5

1. Injection of a fibrinolytic medication to rapidly dissolve clots.
2. Significant Risk of Bleeding.
3. Examples : Streptokinase, Alteplase and Tenectaplase.

Question 6

Additional Treatment to PCI (2B).

Answer 6

1. Dual Antiplatelet Therapy Prior to PCI : Aspirin and Prasugrel (if not taking an oral anticoagulant) OR Clopidogrel (if taking an oral anticoagulant).
2. Drug Therapy During PCI :
   2A. Unfractionated Heparin with Bailout Glycoprotein IIb/IIIa Inhibitor (GPI) if Radial Access.
   2B. Bivalirudin with Bailout GPI if Femoral Access.

Question 7

Additional Treatment to Fibrinolysis (3).

Answer 7

1. An antithrombin drug too.
2. Repeat ECG after 60-90 minutes to see if (at least 50%) ECG changes have resolved.
3. If persistent myocardial ischaemia, consider PCI.

Question 8

Mechanism of Action of Bivalirudin.

Answer 8

Reversible Direct Thrombin Inhibitor.

Question 9

Mechanism of Action of Clopidogrel.

Answer 9

Thienopyridine : Antagonist of P2Y12 ADP Receptor - inhibiting activation of platelets.

Question 10

Contraindications to Thrombolysis (7).

Answer 10

ABCSHIP :
1. A - Aortic Dissection.
2. B - Bleeding.
3. C - Coagulation Disorders.
4. S - Stroke < 3 Months.
5. H - Hypertension (Severe).
6. I - Intracranial Neoplasm/Injury.
7. P - Pregnancy.