Angina is chest pain or discomfort when a part of the heart muscle doesn’t get enough oxygen to cover its metabolic demands. Angina is a symptom of coronary artery disease, where narrowings and blockages in coronary arteries prevent adequate blood supply to the heart muscle. Angina may present as a dull, tight or pressure-type discomfort in the chest which may radiate to the jaw, neck, shoulders or arms. Angina can be triggered by physical activity and stress but sometimes can occur even at rest.
Atherosclerosis (a type of cardiovascular disease) is the most common cause of angina. The blood vessels become narrowed due to fatty plaques, which prevent normal blood supply to the heart muscle. Atherosclerosis risk factors include age, smoking, diabetes mellitus, hypertension, high cholesterol, male gender, positive family history of premature heart disease, physical inactivity and obesity.
Older people are more likely to develop angina. The incidence of angina is higher in men than in women. In England, 1:12 men and 1:30 women aged 55-64 suffer from angina. In the age group above 65, the incidence of angina is 1:7 in men and 1:12 in women.
Coronary atherosclerosis may progress and lead to more frequent anginal attacks or acute coronary syndrome, including unstable angina and myocardial infarction (heart attack). People with angina are also at higher risk of peripheral vascular disease (atherosclerosis in leg arteries leading to intermittent claudication, i.e. cramps in legs on walking) and disease of carotid arteries leading to strokes and TIAs (transitory ischaemic attack, mini-stroke).
There are two main types of angina:
Stable angina is the most common type of angina that occurs during physical activity or mental stress once the degree of exertion or stress exceeds a certain threshold. The underlying mechanism is the disbalance between oxygen supply and demand in the heart. Stable angina develops gradually over time and follows a relatively uniform pattern. The pain is usually promptly relieved by rest or by short-acting nitrates such as GTN (glyceryl trinitrate) spray. Stable angina itself is not a life-threatening condition; however, it indicates the presence of plaques in coronary arteries, which predispose to myocardial infarction.
Unstable angina is a serious type of chest pain that develops rapidly and usually occurs at rest. It may last for up to 20 minutes or more and may not respond to nitrate spray or tablets. Unstable angina may occur in patients with previously known stable angina; however, it may also happen in those without any previous history of heart disease. Unstable angina is a type of acute coronary syndrome. It is a medical emergency because the ongoing lack of oxygen in the heart muscle may lead to a heart attack. The treatment of unstable angina includes medication in the acute stage and revascularization in the long term with coronary angioplasty and coronary artery bypass surgery, discussed in more detail below. Variant or Prinzmetal’s angina (coronary artery spasm) and microvascular angina are other, less frequent types of angina.
Treatment of angina has three main goals:
Several types of medication, including aspirin, beta-blockers, calcium channel blockers, nitrates, nicorandil, ivabradine, ranolazine and statins, can be used to achieve these goals.
Invasive procedures may help when medicines fail to relieve the symptoms of angina. Invasive treatment of angina includes two types of interventions:
Only approximately 1% of patients with stable angina will suffer a fatal heart attack or stroke in any given year. 2.5% of patients may sustain non-fatal heart attack or stroke. The prognosis of unstable angina varies with the severity of the condition and is less favourable.