Clinical symptom/syndrome, rather than a disease – due to an imbalance between oxygen supply and demand of cardiac muscle. Discomfort due to a transient myocardial ischaemia. Incidence of 1/1000/yr in males over 40 years.
Stable angina (exertional angina) – central crushing chest pain on exertion – usually triggered by exertion, relieved immediately by rest. Pain “tight band around chest”; may radiate to neck or jaw – often discomfort in arms; may be worse after meal or in cold weather. Breathlessness is common. Most often due to coronary artery disease (CAD) – especially a partial blockage. Rarely due to valve disease, hypoperfusion in an arrhythmia, anaemia, arteritis
Unstable angina – rapidly worsening and severe angina on minimal or no exertion – pain is prolonged at rest need immediate hospitalisation because of risk of myocardial infarction. The ischaemia is due to sudden reduction in coronary blood flow from thrombus or spasm.
Variant angina (Prinzmetal’s or vasospastic angina) – most often due to coronary artery spasm restricts cardiac blood flow. Pain can occur at anytime, not just on exertion. May occur with stable angina.
Stable angina is due to increased in oxygen demand (demand led ischaemia), Unstable angina due to sudden reduction in blood flow (supply led ischaemia).
Investigations – ECG (resting and exercise); isotope scanning; arteriography
Aim to prevent progression to ischaemic heart disease/myocardial infarction
Screen, assess and modify lifestyle risk factors (stop smoking, reduce alcohol consumption, dietary changes, exercise)
Control of other risk factors (eg hypertension, dyslipidaemia, diabetes mellitus)
Symptomatic relief –
Aspirin (reduces risk of adverse event); sublingual glycerol trinitrate (act immediately vasodilation); beta-adrenoceptor antagonists (reduce heart rate reduce oxygen demand – but may exacerbate cardiac failure and PVD); calcium antagonists (reduce blood pressure and myocardial contractibility reduce oxygen demand).
Coronary angioplasty (balloon is inserted and inflated dilates stenosis); coronary artery bypass graft (CABG) – used to increase blood flow to ischaemic areas of heart.
Acute management of unstable angina – bed rest, aspirin, beta-blocker, heparin, nitrates later follow with modification of risk factors.