Acute Myocardial Infarction

Question 1

Presentations of IHD (CAD)

Answer 1

• Multiple possible initial presentations of IHD
• Chronic stable angina
• Unstable angina
• Acute myocardial infarction
• Sudden death
• Dysrhythmias
• Ischaemic cardiomyopathy presenting as CCF

Question 2

Definition of AMI

Answer 2

Evidence of myocardial necrosis in a clinical setting consistent with acute myocardial ischaemia.

Detectiong of a rise and fall in cardiac biomarkers - preferable cardiac troponin and CK-MB with at least one of:

• Symptoms of acute myocardial ischaemia
• New or presumed new ST-T changes or new LBBB
• Development of pathological Q waves
• Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality
• Identification of intracoronary thrombus at angiography or autopsy

Question 3

Pathogenesis of AMI

Answer 3

Part of acute coronary syndromes which share a common pathogenesis: rupture of a ‘vulnerable’ atherosclerotic plaque in a coronary artery.

Question 4

Left anterior descending STEMI changes

Answer 4

anterior free wall and septum (V1-V4 +/- L1 and aVL)

Question 5

Circumflex and branches STEMI

Answer 5

Lateral free wall (V4-V6, L1 and aVL)

Question 6

Right coronary artery STEMI

Answer 6

Inferior +/- posterior (leads 2, 3 and aVF inferior infarct, marked ST depression V1-V3 reciprocal changes of true posterior infarct)

Question 7

AMI symptoms

Answer 7

Sustained ischaemic discomfort.

Often SOB, nausea, dizzy, anxious.

Question 8

Management of AMI in ER

Answer 8

ECG taken and read within 10’

O2, IV line, sublingual GTN, morphine if needed, continuous ECG monitoring.

ECG divides into STEMI or NSTEMI

Question 9

STEMI

Answer 9

History: sustained symptoms of ischaemia.

ECG taken and read within 10’, IV, O2, exam

ST up = or > 2.0mm in 2 consecutive chest leads or = or > 1.0mm in 2 limb leads in a vascular territory then either to angio or thrombolyse if no contraindications.

Question 10

STEMI guidelines

Answer 10

Angioplasty: if presentation <60’ then door to balloon time <90’

Thrombolysis: presentation less than 12 hours then door to needle time <30’

Question 11

Contraindications to thrombolysis

Answer 11

Absolute: active bleeding, past cerebral harmorrhage, recent (<3 months) stroke, recent major surgery (last 2 weeks)

Relative: marked HTN, pregnancy, known bleeding diathesis, oral anticoagulants, diabetic or haemorrhagic retinopathy, prolonged CPR, recent invasive procedure.

Question 12

Difference in STEMI and NSTEMI management

Answer 12

Reason for different management is that neither primary percutaneous intervention (PCI) nor thrombolysis have shown a clear cut survival advantage with NSTEMI whereas there is a very clear cut survival advantage with both in STEMI.

Primary PCI all other factors being equal is superior to thrombolysis and in hospitals equipped and staffed for PCI is the preferred treatment.

Question 13

Complicatiosn of AMI

Answer 13

• Dysrhythmias VT, VF, AF, AV block
• Severe systolic dysfunction: cardiogemic shock and CCF
• Myocardial rupture
• Mitral regurgitation
• VSD
• Pericarditis
• Dressler’s syndrome

Question 14

Dressler’s syndrome

Answer 14

• Also known as postmyocardial infarction syndrome.
• It is a secondary form of pericarditis that occurs in the setting of injury to the heart or the pericardium. It consists of a triad of features: fever, pleuritic pain and pericardial effusion.