Myocardial infarction

Question 1

DDx for chest pain

Answer 1

Cardiovascular: unstable/stable angina, MI - STEMI / NSTEMI, infection - pericarditis, endocarditis
Pulmonary: Pneumothorax, PE, secondary to infection e.g. pneumonia
MSK: secondary to trauma
Psychogenic

Life threatening: cardiac tamponade, Pneumothorax and PE

Question 2

Pathophysiology of MI

Answer 2

Infarction secondary to ischemic which can be divided into increased demand and supply insufficiency secondary to obstruction/ thrombus formation.

Atherosclerosis - lumen narrowing with intimal changes

• Endothelial injury secondary to biomechanical stressors
• macrophages migrate + hypercholesterolemia

Question 3

MI risk factors

Answer 3

Modifiable: hypercholesterolemia, hyerlipidemia, sedentary lifestyle, high meat and low fibre diet, smoking, alcohol

Non-modifiable: pre-existing comorbidities (e.g. DM), family history, age and gender

==> Australian Absolute Cardiovascular Risk Chart (Framingham RIsk equation) -> risk factor stratified estimation for % risk of having a heart attack in the next 5 years

Question 4

Complications

Answer 4

Ischemic - reinfarction, extension, distal ischemia downstream from obstruction
Arrhythmic - electrical activity is affected, atrial or ventricular fibrillation
Mechanical - valvular incompetence, papillary muscle rupture, interventricular septum rupture

Question 5

Complications

Answer 5

Ischemic - reinfarction, extension, distal ischemia downstream from obstruction

Arrhythmic - electrical activity is affected, atrial or ventricular fibrillation

Mechanical - valvular incompetence, papillary muscle rupture, interventricular septum rupture

Inflammatory - Dressler’s sydrome - autoimmune pericarditis that happens 1-8 weeks after MI