As one of the most common types of heart disease, coronary heart disease (CHD) – also referred to as Coronary Artery Disease (CAD) – is one of the UK’s top causes of death, and the top cause of premature death. In fact, in 2019 it was the main cause of death across the globe (British Heart Foundation). This is because when not properly treated, CHD can have severe complications to our health with results such as heart attacks, strokes, arrhythmias and heart failure. So what is coronary heart disease and how can it lead to these possibly life-threatening conditions? In this article, we will explore these questions further. 

What is coronary heart disease?

Coronary heart disease (CHD), or coronary artery disease (CAD), makes up between 33–50% of cases of heart disease.¹ It refers to when the blood flow to your heart is obstructed and reduced. 

Blood is supplied to your heart via your coronary arteries. During our lifetime fatty deposits (referred to as plaque) can build up inside the walls of these arteries – a process known as atherosclerosis. 

CHD is a term used to describe when these coronary arteries have narrowed due to these fatty deposits in their walls, and therefore cannot get enough blood to the heart. 

Symptoms of coronary heart disease

According to the NHS, common symptoms of CHD can include: 

• Breathlessness
• Pain in the chest (angina)
• Neck, shoulder, jaw or arm pain 
• Faintness 
• Nausea

However, it is important to be aware that not everybody with CHD presents with symptoms. For some patients, they do not experience any symptoms of the disease until they suffer their first heart attack. 

Treatment options for coronary heart disease

Anybody with coronary heart disease must receive treatment from a specialist. The treatment options can vary depending on each case and each patient’s health, but common treatment options can include: 

• Medication 
• A coronary angioplasty/stent 
• Heart bypass surgery 

It is also recommended that alongside these treatment options, those with CHD make lifestyle changes too – such as giving up smoking, staying active and eating healthily.

When CHD is not treated, it can lead to various (sometimes very serious) complications. 

Complications of coronary heart disease

People with CHD are at an increased risk of serious heart problems. The fatty deposits which narrow the coronary arteries in CHD can lead to cardiovascular complications such as heart failure, heart attacks, arrhythmias and strokes.² 

Heart failure

Heart failure, which is also known as ‘cardiac insufficiency’ (or less commonly ‘congestive heart failure’) is a term describing when the heart cannot pump enough blood around the body because it has become weakened or stiff (NHS).

Heart failure can have different consequences according to the side (ventricle) of the heart that it affects. With right-sided heart failure, there is a buildup of blood in the veins carrying blood to the heart from the rest of the body which can cause oedema (swelling) in the legs, abdomen and/or liver.

In the case of left-sided heart failure, this blood buildup is in the vessels carrying blood away from the lungs, causing breathlessness.³ 

There are two classifications of left-sided heart failure:

• Heart failure with reduced ejection fraction (systolic failure) – the heart muscle is weakened and cannot pump blood around the body, leaving the organs with an insufficient supply of oxygen
• Heart failure with preserved ejection fraction (diastolic failure) – the heart muscle is not weak, but the tissue has stiffened and cannot expand enough after the heart muscle contracts to fill with blood, meaning that not enough blood is flowing around the body

It is also possible for heart failure to affect both sides of the heart, and this is referred to as biventricular heart failure.⁴

Previously, it was thought that high blood pressure or heart valve disease was the most frequent cause of heart failure. However, the Framingham Heart Study suggests that CHD is the most common cause.⁵ This tells us that the majority of cases of heart failure are caused by CHD, making heart failure a very common (not to mention serious) complication of the disease.  

Whilst certain trials have proved how effective treatment (with medications or devices) can be in saving the lives of heart failure patients with CHD⁶, it is of course preferable to treat CHD before it can develop into heart failure. 

Heart attack 

Another common complication of CHD is a heart attack. A heart attack (myocardial infarction) happens when a part of the heart muscle – the myocardium – does not get enough oxygen due to partially or fully blocked arteries. This lack of oxygen can result in the cells in the myocardium (heart muscle) dying and causing a serious threat to life.⁸

There are 2 types of heart attacks: 

• ST-elevated myocardial infarction (STEMI) – the blood supply is interrupted for a long time and requires urgent treatment to remove the blockage in the artery
• Non-ST-elevated myocardial infarction (NSTEMI) – a ‘mini heart attack’ where some of the blood supply is cut off, without treatment it could turn into a STEMI

When suffering a heart attack, somebody may struggle to breathe, have pain in their chest, feel sick or faint, sweat a lot, and/or experience arm/shoulder/neck pain. 

If you suspect you or somebody else is having a heart attack, you should call the emergency services straight away. 

So, how does CHD link to heart attacks? The fatty deposits built up in the arteries in CHD cause the arteries to become blocked, thus interrupting the blood supply to the heart and causing a heart attack. CHD is the main cause of heart attacks (NHS). 

Arrhythmias 

When somebody has CHD and their heart is receiving insufficient blood (and therefore not enough oxygen), the cells in their heart muscle can become damaged. This damage to the cells can cause their heart rate to become too fast, too slow and/or irregular.⁴ This is called an arrhythmia.  

There are many different types of arrhythmias, but the most common are: 

• Atrial fibrillation (AF) – a heartbeat which is faster than normal and irregular
• Supraventricular tachycardia – where the heart suddenly beats unusually fast at rest
• Bradycardia – a heartbeat which is slower than normal
• Heart block –  a heartbeat which is unusually slow and can result in somebody fainting

CHD is a significant risk factor for atrial fibrillation, meaning that people with CHD are at a much higher risk of developing atrial fibrillation.⁹

Stroke 

Ischemic strokes have also been cited as complications of CHD. 

An ischemic stroke happens when the blood supply to the brain is cut off due to a blockage in the arteries caused by atherosclerosis – the buildup of fatty deposits (plaque) in the artery walls.

There are two types of ischemic stroke caused by this: 

• Atherothrombotic stroke – plaque ruptures in a blood vessel, causing blood clots to form there, blocking the blood flow to the brain
• Embolic stroke – a blood clot breaks away from where the rupture was and is carried through the bloodstream, lodging in an artery leading to the brain and blocking blood flow

Embolic strokes are also (more commonly) caused by blood clots that have been formed as a result of atrial fibrillation (American Stroke Association). 

People who have CHD are 2x more likely to have a stroke than those who do not have CHD (British Heart Foundation). This could be down to the fact that CHD, by its very nature, is the buildup of plaque in the coronary arteries, a direct cause of strokes. 

In addition, many CHD patients develop atrial fibrillation which is also a very common cause of strokes – atrial fibrillation increases your risk of stroke x5 (NHS).

Complications: key takeaways

The plaque buildup in coronary arteries that happens in CHD can seriously disrupt the blood flow to the heart. With this lack of blood and oxygen being pumped where it needs to go in the body, serious complications can arise. Seeking treatment for CHD is vital to help avoid these complications developing. 

Summary

• Coronary heart disease refers to when plaque builds up in your coronary arteries and obstructs the blood flow to the heart
• Symptoms can include breathlessness, chest pain, arm/shoulder/neck/jaw pain, and nausea
• It can be treated with medications, an angioplasty/stent and bypass surgery
• If untreated, the blockage in the arteries can cause serious complications such as: 
  • Heart failure: where the heart cannot pump enough blood around the body
  • Heart attacks: where the blood/oxygen supply to the heart is interrupted
  • Arrhythmias: when the heart beats abnormally fast/slow or irregularly
  • Strokes: where the blood/oxygen supply to the brain is interrupted
• See your doctor if you think you may have coronary heart disease to receive treatment to help avoid these serious complications