Clinical pharmacology of stable coronary artery disease Flashcards
Features of ischaemic heart disease
- It is the most common cause of death in pre-retirement males
- Acute coronary syndromes
- Stable coronary disease
Acute coronary syndromes
- Myocardial syndromes: STEMI or NSTEMI
- Unstable angina pectoris
Stable coronary artery disease examples
- Angina pectoris
- Silent ischaemia
Risk factors of ischaemic heart disease
- Hypertension
- Smoking
- Hyperlipidaemia
- Being male
- Post-menopausal females
Features of Stable coronary artery disease
- SCAD arises as a result of a mismatch between myocardial blood/oxygen supply and demand
- Attacks of angina (chest pain) may be precipitated by any stress which increases cardiac work and myocardial oxygen demand
- Anything which increases heart rate, stroke volume or blood pressure
What are determinants of demand ischaemia (ischaemia during stress)?
- Heart rate
- Systolic blood pressure
- Myocardial wall stress
- Myocardial contractility
What are determinants of supply ischaemia (ischaemia at rest)?
- Coronary artery diameter and tone
- Collateral blood flow
- Perfusion pressure
- Heart rate (duration of diastole)
Features of Hyperlipidaemia
- Atherosclerosis at the start
- Disease of the muscular arteries (not veins)
- Progressive deposition of cholesterol esters
- Accounts indirectly for half of annual mortality
- Lesions start as fatty streaks (aged 20)
- Fibrous plaque
- Most of the changes are in the intimal layer
- Most of the foam cells are of smooth muscle origin
- Necrotic core
- Fibrous cap
How can drugs help to correct imbalance?
- Decreasing myocardial oxygen demand by reducing cardiac workload:
Reduce heart rate
Reduce myocardial contractility
Reduce afterload - Increasing the supply of oxygen to ischaemic myocardium
What is the purpose of drug treatment?
- Relieve symptoms
- Halt the disease process
- Regression of the disease process
- Prevent myocardial infarction
- Prevent death
Definition of stable angina
A clinical syndrome of predictable chest pain or pressure precipitated by activities such as exercise or emotional stress, which increase myocardial oxygen demand
Types of drugs used in drug therapy of angina
- Rate limiting
- Vasodilators
- Anti-platelet
- Potassium channel openers
- Cholesterol lowering agents
Rate limiting drugs used in drug therapy
- Beta-adrenoreceptor antagonists
- Ivabradine
- Calcium channel blockers
Vasodilators used in drug therapy
- Calcium channel blockers: reduce afterload on the heart
- Nitrates e.g. GTN: oral, sublingual
What is the main potassium channel opener used in angina?
Nicorandil
Nitrates used in angina
- Short duration: sublingual nitroglycerin
- Intermediate: oral nitroglycerin
- Long duration: transdermal nitroglycerin
Anti-platelet drugs used in angina
- Aspirin
- Clopidogrel
- Tigagrelor
Cholesterol lowering agents used in angina
- HMG CoA reductase inhibitors
- Fibrates
Beta blockers used in angina and features
Bisoprolol, Atenolol
- Beta blockers are reversible antagonists of the Beta1 and Beta2 receptors
- Newer drugs are cardioselective acting primarily on the beta1 receptors
- Block the sympathetic system
What do beta blockers actually do?
- Decrease three major determinants of myocardial oxygen demand: heart rate, contractility, systolic wall tension
- Also allow improved perfusion of the subendocardium by increasing diastolic perfusion time
- Decrease the force of myocardial contraction
- Decrease the cardiac output
- Decrease the velocity of contraction
- Decrease blood pressure
- Protect cardiomyocytes from oxygen free radicals formed during ischaemic episodes
What is the rebound phenomena of beta blockers?
- Sudden cessation of beta blocker therapy may precipitate myocardial infarction
- Those at risk include patients with angina and men over 50 years receiving beta blockers for other reasons