Coronary Artery Disease and Myocardial Infarction Flashcards
Define ischaemic heart disease disease?
An imbalance between myocardial oxygen demand and supply from the coronary arteries
What conditions fall under the bracket of acute coronary syndrome?
Unstable angina
NSTEMI
STEMI
Coronary artery syndrome is caused by atherosclerosis. What is the pathophysiology of atherosclerosis?
The endothelium becomes injured due to hypertension, tobacco etc. LDL particles are able to leak into the intimal layer of the vessel and become oxidised. Oxidised LDL act as a pro-inflammatory antigen, inducing an immune response. Macrophages enter the arterial walls and phagocytose oxidised LDL particles to create foam cells. The accumulation of foam cells underneath the endothelium creates a fatty streak. Platelet and endothelial cells release PDGF, FGF. and TGF-beta which stimulate smooth muscle proliferation and migration into the tunica intimal. This proliferation stimulates the production of extracellular matrix which results in the formation of a fibrous cap overlying the lipid core. This plaque can obstruct the lumen and may rupture. If the plaque ruptures (due to MMP degradation of the fibrous cap) platelets form a fibrin clot at the site of rupture which further occludes the vessel
What are the non-modifiable risk factors for atherosclerosis?
Age
Family history
Black ethnicity
What are the modifiable risk factors for atherosclerosis?
Hypertension
Diabetes mellitus
Smoking
Dyslipidaemia
How far obstructed does the lumen of the coronary artery need to be to cause symptoms of angina?
70% stenosis
What are the less common causes of ischaemic heart disease despite atherosclerosis?
Coronary. artery embolism
Vasculitis
Vasospasm
What are the risk factors for coronary embolism?
Atrial fibrillation
Infective endocarditis
Left atrial / ventricular thrombus
Cardiac catheterisation
What is the most likely cause of coronary artery disease in children?
Kawasaki disease (this is a type of vasculitis)
How is it possible for an atherosclerotic plaque cause. near-total occlusion of a coronary artery without causing infarction?
Because atherosclerosis develops slowly overtime which allows collateral vessels to develop
What are the three key characteristics of classical angina pain?
Substernal chest discomfort
Provoked by exercise or stress
Relieved with rest or glyceryl trinitrate
What groups of people are more likely to present with atypical symptoms of coronary artery disease or acute coronary syndrome?
Women
Patients with diabetes
Elderly people
What are the possible symptoms of an atypical angina / coronary artery. disease presentation?
Nausea
Vomiting
Mid-epigastric discomfort
Sharp chest pain
Where does angina pain typically radiate to?
Neck, jaw, epigastrium or arms - typically on the left side
Describe the character of anginal pain?
Tightness, pressure, heaviness
What are the associated symptoms of angina?
Dyspnoea Nausea Vomiting Perspiration Light-headedness Fatigue
What are the exacerbating factors of. angina?
Exercise Stress Sexual activity Tachycardia of any cause Metabolic demands of fever / thyrotoxicosis / hypoglycaemia
What examination findings might you expect in coronary artery disease?
Physical examination is. often normal
May be signs of associated conditions e.g. heart failure, valvular disease or hypertrophic cardiomyopathy
May be signs of non-coronary atherosclerotic disease e.g. diminished pedal pulses, carotid bruit
Signs of hypercholesterolaemia - xanthelasma
Hypertension
What initial laboratory tests should be conducted in suspected stable angina?
Haemoglobin Blood. glucose Lipid Panel U&Es TFTs
Besides blood tests, what investigations should be conducted for suspected. stable angina?
Resting ECG
Resting echocardiogram
+/- exercise stress testing, SPECT, PET, CCTA, invasive coronary angiography
What drug is used. to terminate acute episodes of angina or for prophylaxis. before activities known to induce angina?
Sublingual glyceryl trinitrate
What is the onset of action of sublingual glyceryl trinitrate?
Minutes
What is involved in education and lifestyle modification for stable angina?
Weight management - increasing exercise, healthy diet
Smoking cessation
Stress and depression recognition and management
Annual influenza vaccine
What is involved in medical management of stable angina?
Antiplatelet therapy Beta blockers RAAS antagonists Lipid management Blood pressure control Diabetes management
What drug is often used for anti-platelet therapy for. stable angina?
Low dose aspirin
For which patients with stable angina. should ACE inhibitors be prescribed?
Those with hypertension, diabetes mellitus, left ventricular ejection fraction <40% or CKD
What drug is used for lipid management in stable angina?
High intensity statins
Describe the pathophysiology of coronary steal syndrome?
This can occur when a vasodilation medication is given to an individual with stable angina. The vasodilator results in vasodilation of all the coronary arteries, except the ones which are obstructed because these arteries are already maximally dilated beyond the point of obstructed. As a result blood is diverted away from the ischaemic myocardium to non-ischaemic areas, further worsening the ischaemia