Stable and Unstable Angina: What's the Difference?

Angina is a common problem that affects hundreds of thousands of older people in the UK. As many as 20 000 new cases are diagnosed each year. The condition is part of a whole set of chronic illnesses that are due to atherosclerosis – the build up of fatty plaques on the inner walls of the arteries.

Atherosclerosis is a lifestyle disease and is very common in countries with a typical ‘Western’ lifestyle. In developing countries it is less common, but is becoming more prevalent as economic advances there are leading people to adopt the same sort of diet. Eating a lot of fat, particularly saturated fat, highly processed foods, lots of refined sugar can lead to a whole range of chronic diseases of middle age including diabetes, heart disease and an increased risk of strokes.

When atherosclerosis affects the arteries that supply heart muscle, the increased narrowing reduces the blood flow to the atrial and ventricular muscles. This fatigues the heart; just as your leg muscles hurt and get tired when running, fatigue in heart muscle causes tissue damage and pain – and this is experienced as a tight feeling in the chest. This can fade and become a dull ache, or worsen into an intense pain just underneath the breast bone. Whether mild or severe, an angina attack can be very frightening.

Acute Angina – What Causes and Attack?

Angina attacks occur when the narrowing of one or more of the coronary arteries starts to cut off the blood supply to the heart muscle. The artery is not completely blocked – the blood is just not able to pass through as quickly, so delivery of oxygen and nutrients is slowed down. Typical symptoms include chest pain and breathlessness when doing something strenuous – running upstairs, rushing to go somewhere, doing some exercise when you aren’t used to it.

The pain is caused when cells in the heart muscle become distressed and some cells may actually die. This releases signals that alert the body that something is very wrong; inflammatory cells and mediators rush to the scene and the result is pain.

Stable Angina and Activity

Stable angina is defined as this type of chest pain that comes on only during exertion or extreme emotional upset. The attack can be quickly relieved using a drug called glyceryl nitrate, which comes in the form of a throat spray or a dissolvable tablet for fast acting relief. Stable angina causes temporary symptoms – these usually fade when the strenuous exercise stops or are relieved by one dose of glyceryl nitrate.

Having stable angina is a warning that the cardiovascular system is not as healthy as it might be. As well as medical treatment to reduce the risk of developing blood clots that could lead to a heart attack or stroke, people with stable angina are encouraged to become more active. Starting with gentle exercise at first is recommended, building up gradually until you can do about 30 minutes of reasonably good exercise such as brisk walking at least five times each week.

Recognising Unstable Angina

If the pain from angina becomes more frequent, it starts to become more persistent or it comes on at rest rather than just when exercising, it is more of a cause for concern. Unstable angina can occur without warning at any time and it is a very serious warning that one or more of the coronary arteries has become almost completely blocked. The heart muscle is struggling harder than ever to get enough oxygenated blood.

Unstable angina is grouped together with mild and severe heart attacks under a collective term – acute coronary syndrome. This is always an emergency situation and someone with the pain of angina, which starts when resting or when sleeping, should always be taken to the nearest Accident and Emergency department to be checked out. They may need life saving immediate treatment to relieve the blockage in their coronary artery to prevent a heart attack.