Acute Myocardial Infarction Frequently Asked Questions

What is a silent myocardial infarct?
A painless infarct, common in diabetics and the elderly; it may present with complications of myocardial infarction.

What is Levine's sign?
In acute myocardial infarction the patient often describes the pain by illustrating a clenched fist.

What are the major risk factors for an acute MI?
· Smoking.
· Hypercholesterolaemia.
· Diabetes.
· Hypertension.

What are the complications of myocardial infarction?
· Extension of infarct and post-infarct ischaemia.
· Rhythm disorders: tachycardia, bradycardia, ventricular ectopics, ventricular fibrillation, atrial fibrillation and tachycardia.
· Heart failure: acute puhnonary oedema.
· Circulatory failure: cardiogenic shock.
· Infarction of papillary muscle: mitral regurgitation and acute puhmmary oedema.
· Rupture of interventricular septum.
· Left ventricular aneurysm.
· Mural thrombus.
· Thromboembolism: cerebral or peripheral.
· Venous thrombosis.
· Pericarditis.
· Dressler's syndrome, characterized by persistent pyrexia, pericarditis, pleurisy.
What are TIMI grades?
Grades determined in the Thrombolysis in Myocardial Infarction trial (TIMI) that measure coronary blood flow and luminal narrowing:
· Grade 0: no flow of contrast beyond the point of occlusion.
· Grade I: penetration with minimal perfusion (contrast fails to opacify the entire coronary bed distal to the stenosis for the duration of investigation).
· Grade 2: partial perfusion (contrast opacities the entire distal coronary artery, but the rate of entry or clearance or both is slower in the previously blocked artery than in nearby normally perfused
vessels).
· Grade 3: Complete perfusion (contrast filling and clearance are as rapid in the previously blocked vessel as in normally pert'used vessels).

Why is the Asian population in Britain susceptible to premature myocardial infarction ?
Premature ischaemic heart disease in migrants from the Indian subcontinent is associated with insulin resistance. The site of this defective insulin action has been localized to the skeletal muscle by means of positron emission tomography (Baliga RR et al. Positron emission tomography localizes insulin resistance to skeletal muscle in premature coronary heart disease.