Angina Without High Blood Pressure

What is Angina?

Angina, also known as angina pectoris, is a type of chest pain caused by impaired blood flow to the heart muscles.¹ This occurs due to a reduction in the blood flow in the arteries of the heart, and therefore oxygen delivery, and can be a sign of heart disease.²

The main cause of angina is coronary artery disease, which obstructs the arteries, leading to less blood flowing to the heart and consequently affecting the functioning of this organ and causing chest pain.

Depending on the severity of the coronary heart disease, the obstruction can lead to heart attack, also known as myocardial infarction, and lead to irreversible damage to the myocardium (heart muscle) and the other structures of the heart.

Signs and Symptoms 

Angina itself is a symptom presented most of the time as chest pain, which can also be felt as tightness, pressure, heaviness or squeezing sensation, mostly on the central or left side of the chest.³ However, this discomfort can also occur or radiate to the shoulders, arms (especially the left side), neck, jaw, abdomen, and back.¹

Some other symptoms associated with angina are:

• Dizziness
• Breathlessness
• Nausea
• Sweating
• Fatigue⁴

An angina attack is usually triggered by exertion or stress, and tends to go away with rest. This type is known as stable angina. Sometimes angina occurs without a trigger and even when resting, which is known as unstable angina.²

Causes and Risk Factors

As explained above, angina is caused by reduced blood supply into the heart muscle, and the main cause of it is a blocked artery of the heart. Arteries are mainly blocked by plaques with fatty substances causing a disease known as arteriosclerosis of the coronaries (blood vessels of the heart). The main risk factors for developing this cardiovascular disease are:

Figure: Risk factors for Cardiovascular Diseases

Created by Aastha Malik

However, angina can also be caused by some other conditions not directly related to coronary heart disease.

Conditions that Cause Angina

Despite coronary disease being the main cause of angina symptoms, there are some other less common causes that also need to be discussed.

One of them is known as Vasospastic or Variant Angina, in this case, there is no plaque blocking the blood flow in the heart arteries but the coronaries can narrow due to a spasm of the vessel, limiting the supply of oxygen-rich blood into the heart and causing the pain. This condition is also known as Prinzmetal’s angina.⁴ The symptoms might be triggered by cold weather, emotional stress, medicines, smoking, or cocaine use.⁷

The other one is known as Microvascular Angina or Cardiac Syndrome X, mainly caused by microvascular disease, but can also be triggered by anxiety, emotional stress and exercise. Spasms to these microvessels can cause pain, but pain can also be caused by plaques blocking these small arteries. Symptoms like chest pain, can last longer, and breathlessness, fatigue, and sleep problems can also occur.^4,8

Role of Coronary Artery Disease

Considering that the main cause of angina pectoris is coronary heart disease, it is important to understand its mechanisms. This disease is caused by the build-up of plaques in the blood vessels. These plaques are mainly formed by cholesterol, but other substances are also involved.⁹

These fatty deposits are known as atheroma and the process of building plaques is known as atherosclerosis.¹⁰ These plaques develop over years and cause narrowing and blockages in the coronary blood vessels, which limits the blood flow to the heart muscle.¹¹

This narrowing can lead to angina symptoms and, if not treated, the blockage can lead to myocardial infarction, causing damage to the heart, which sometimes might be irreversible and result in heart failure.

Diagnosis and Treatment 

If you believe you may have the symptoms of angina, you should book an appointment with your healthcare provider to have a health assessment and some tests performed. Tests that can help with the diagnosis of angina are:

• ECG: a test that checks the heart rhythm and electrical activity. Some changes in the pattern can be suspected of angina.
• Exercise ECG or stress ECG: monitor the electrical activity of the heart during exercise, and changes in the electrical pattern or chest pain can indicate angina.
• Computed Tomography Coronary Angiography: scan to check inside the heart’s blood vessels and identify blockages or narrowings.
• Cardiac Magnetic Resonance Imaging (MRI): this can help to see reduced blood flow into cardiac areas.
• Echocardiogram: helps to identify heart damage caused by reduced blood flow.
• Nuclear stress test: also helps to identify areas where the blood is not flowing normally.³

The treatment for angina will depend on which type it is, stable angina will generally require medications to control pain and the risk factors and medicines for coronary heart disease such as

• Glyceryl trinitrate spray
• Medicines to control cholesterol (Statins)
• Medicines to control high blood pressure (beta blockers and calcium channel blockers)
• A low dose of aspirin
• Unstable angina and patients with a high risk of heart attack might need other interventions like
  • Angioplasty with stenting.
  • Coronary artery bypass graft.¹²

Can You Have Angina Without High Blood Pressure?

High blood pressure, although highly associated with angina, might not be present in some of the cases. Some angina causes are not directly related to high blood pressure (Variant angina, for example) and even people with microvascular angina might have normal blood pressure.

However, high blood pressure is a risk factor and cause of coronary heart disease. The stress caused by the high pressure in the walls of the vessels triggers an inflammation process that is related to the building of the fatty plaques, and it is very unlikely to find a person with coronary artery disease without high blood pressure, although not impossible.

Effect of High Blood Pressure on Angina

There are different ways high blood pressure can affect and make angina symptoms worse. First of all the pressure on the vessels can help the inflammation process leading to atheroma, but can also contribute to reducing the elasticity of these arteries, making the narrowing even worse.¹³

High blood pressure also makes the heart work harder to pump the blood, over time, this can make the muscle thickens and increase the demand for oxygen to the heart. This can alter the balance between supply and demand, making angina worse and increasing the risk of myocardial ischaemia.

Preventing High Blood Pressure

A healthy lifestyle is the best option to prevent high blood pressure, also known as hypertension, and can help to prevent a lot of other diseases caused by it, like angina, for example.

Figure: Lifestyle Changes

Created by Aastha Malik

Simple lifestyle changes can help you improve your health and prevent a lot of diseases, especially cardiac diseases.¹⁴

What is Silent Ischaemia?

Silent ischaemia happens when the reduced blood flow to the heart does not cause any symptoms of angina. Although the oxygen flow to the heart is reduced, this doesn’t trigger a response, and people with angina can have episodes of silent ischaemia.¹⁵

Although angina symptoms might be worrying, they can lead us to get a diagnosis and begin treatment for the condition. However, a person with silent ischaemia might suffer a myocardial infarction without previous warning and not even know that they had coronary heart disease. Silent ischaemia can thus be very dangerous for any person who suffers from it.

Diagnosis

Silent ischaemia might not have classic symptoms, but it is also caused by the same things as angina. Therefore, the diagnosis of this condition is very similar to the tests performed to diagnose angina, but the diagnosis is generally incidental since it might not be suspected without the classic signs. The tests are:

• ECG
• Exercise ECG or stress ECG
• Computed Tomography Coronary Angiography
• Cardiac Magnetic Resonance Imaging (MRI)
• Echocardiogram
• Nuclear stress test

Symptoms

Silent ischaemia is often characterized by a lack of symptoms. However, in some cases, people might present very unspecific symptoms, such as:

• Fatigue
• Weakness
• Feeling faint or collapsing 
• Dizziness
• Nausea

People who suffer from diabetes are the most likely to also suffer from silent ischaemia, and may be at a greater risk of a silent heart attack, as diabetes can lead to nerve damage which reduces sensory perception, including pain perception.

Preventing Angina and Ischaemia

The prevention of angina and ischemia focuses mainly on controlling risk factors and treating the primary cause of angina. This may involve:

• Following a healthy diet
• Exercising regularly
• Controlling high blood pressure
• Not smoking 
• Limiting the amount of alcohol consumption
• Complying with medications
• Controlling cholesterol and sugar levels
• Reducing stress levels 

Summary

Angina is a condition caused by the impaired flow of blood to the heart, mainly caused by narrowing and blockages of the heart arteries. There are different types of angina, and not all of them are caused by coronary artery disease.

High blood pressure is not necessarily present in all types of angina, but it is one of the causes of coronary heart disease, which is the condition mostly associated with angina. Hypertension can also aggravate the state of the heart vessels and worsen angina symptoms.

There are some situations in which the ischaemia provoked by the decreased blood flow doesn’t show any symptoms, such as with a condition known as silent ischaemia, to which patients with diabetes are particularly susceptible.

The best forms of prevention of high blood pressure, angina, and ischaemia are lifestyle changes, including a healthy diet, regular exercise, and other healthy habits like not smoking and limiting alcohol consumption.