Diagnosing angina through the ages

Angina is a condition characterised by a feeling of pressure, tightening or squeezing in the chest. Although many people associate the condition with the stresses with modern life, the condition has been recorded as far back as ancient times. In this article, leading consultant cardiologist Dr Khalid Barakat gives fascinating insight into how angina has been diagnosed across history as well as expertly explaining modern diagnosis and treatment methods.

What is angina and what are the main symptoms?

Angina pectoris is a cause of chest pain and literally means a constricting sensation of the chest. Although considered to be caused by modern living, it was described by the ancient Egyptians as long ago as 1500 BC. They did not know that it was due to heart disease.

The Greek physician Hippocrates (460-370 BC - also famous for the Hippocratic Oath) first used the term angina. English physician Heberden described the symptoms of angina in one hundred patients in 1768. He noted that the majority were men and older than fifty. The description published by Heberden is as true today as it was then. Patients with angina present with a constricting sensation in the centre of the chest which may radiate to the arms and/or jaw and typically occurs with exertion or can be triggered by emotional stress. It is relieved within a few minutes with rest.

How does angina differ from a heart attack?

Angina is typically caused by fatty deposits within the arteries that supply the heart (the coronary arteries). Jenner described the first possible cause of angina when he undertook an autopsy of two patients who had died from angina and discovered that their coronary arteries 'had a fleshy tube within the coronary arteries with dispersed ossified material within it.'

The heart is a pump and the muscle of the heart energy needs blood for oxygen and nutrients to power it. In general, in patients at rest with stable angina there is sufficient supply of blood to the heart muscle to meet its needs. With exercise or emotional stress when the heart begins to pump harder it needs more oxygen and nutrients. If the narrowings in the coronary arteries are severe enough then the heart muscle cannot get sufficient blood flow to meets its needs. As a consequence a waste product called lactic acid builds up in the heart muscle which gives the characteristic chest pain of angina. As the person rests and the heart rate reduces, this waste product is removed and the pain disappears.

A heart attack is different to angina in that it is caused by a rupture in the cap of the fatty deposits in the coronary arteries which exposes the fatty deposits to blood. This triggers a clotting response by the blood as a breach in the artery is perceived. If this clot is extensive enough to block the artery then a heart attack will result. Typically the blockage needs to occur for a minimum of thirty minutes before a heart attack (due to death of heart muscle cells) starts to occur. After six hours of a blocked artery most of the heart muscle in the area supplied by the heart artery will be permanently damaged. A heart attack will typically result in a permanent decrease in heart muscle strength whilst angina will not.

How is angina diagnosed?

A diagnosis of angina begins with a review with a cardiologist who will take a history and see if this fits with a diagnosis of angina. They will examine the patient to see if there are any significant abnormalities. Patients will have an ECG but a normal ECG will not exclude the diagnosis.

The patient will also typically have an echocardiogram to look at the heart muscle strength and also to exclude causes of angina that are not due to narrowed coronary arteries such as aortic stenosis (narrowing of the aortic valve).

To make a definitive diagnosis of angina, the cardiologist may do a functional test or an anatomical test. An anatomical test looks to see if there are narrowings in the heart arteries and includes a coronary angiogram or a CT coronary angiogram.

A functional test includes a myocardial perfusion scan, a cardiac MRI with perfusion or a stress echo. The first two look at blood flow into the heart muscle with stress and exercise whilst the stress echo looks at the strength of heart muscle with increasing exercise and stress. A failure of heart muscle to get the increase in blood required for its needs with exercise results in a failure of heart muscle to beat stronger with exercise in the area supplied by the artery with a significant narrowing.

What are the treatment options for angina?

The mainstay of therapy for angina is medical. The treatments for angina are divided into:

• prognostic - those that improve survival
• symptomatic - those that alleviate symptoms

Prognostic medications include statins and aspirin. Treatments for symptoms include beta blockers, nitrates and calcium channel blockers.

Coronary artery bypass surgery has been shown to improve survival of a select group of patients with extensive heart disease particularly with a weakened heart muscle. Heart surgery is also excellent in alleviating symptoms for patients with extensive disease who do not settle with medication.

Coronary angioplasty is an excellent treatment for alleviating symptoms in patients with stable angina and has shown to improve survival in patients with heart attacks and unstable angina.

What are the different types of angina? Which one is the most concerning?

• Stable angina - patients only have symptoms with exercise or emotional stress which is alleviated with rest
• Unstable angina - the pattern of chest pain begins to become less predictable and can occur at rest and for longer periods after exercise (this type of angina is very concerning because it can progress to a heart attack) 
• Post-prandial angina - symptoms occur after meals, typically on walking (caused by the fact that blood is diverted to the stomach following a meal)
• Microvascular angina - caused by significant narrowings in the coronary arteries (previously called syndrome X) and thought to be due to problems with blood flow through the micro-vaculature and hence its more modern name of coronary microvascular disease (CMD)

Is angina dangerous or life-threatening, why?

Once appropriately assessed and treated with medication, stable angina has a good outcome. Unstable angina is dangerous as it can deteriorate and cause a heart attack (myocardial infraction).

If you are concerned about angina or your heart health, you can book a consultation with Dr Barakat by visiting his Top Doctors profile.