How many beats per minute is a heart attack?

Overview

A heart attack (scientifically known as a myocardial infarction) is a medical emergency branched under the umbrella category of cardiovascular disease. Cardiovascular diseases are conditions related to the heart and blood vessels. According to The World Health Organisation, Cardiovascular disease is the leading cause of death worldwide. ⁽¹⁾

A heart attack is a severe and life-threatening emergency. However, with early symptom detection, treatment and proper management, it is possible to recover and live a healthy life. 

Signs and symptoms of a heart attack

Although not always, usually the onset of a heart attack comes with warning signs. It is essential to be aware of them as a heart attack is a medical emergency and requires urgent care. Five classic symptoms commonly occur during the onset of a heart attack: ⁽²⁾ 

• Pain or discomfort in the jaw, neck or back
• A feeling of lightheadedness or faintness
• Chest pain or chest discomfort that can happen continuously or come and go. It can feel like a squeezing sensation or a feeling of pressure. 
• Pain or discomfort in the arms or shoulders. The discomfort can appear in one or both arms 
• Shortness of breath 

Chest pains can occur during a heart attack or in the hours or weeks before a heart attack. It happens because there is restricted blood flow to the heart and may serve as an early warning sign. These chest pains typically do not disappear even when resting and are termed ‘Angina’. It is essential to recognise this symptom so that medical advice can be sought. 

Interestingly, it has been found that heart attack symptoms can vary between men and women. Left-arm, jaw and neck discomfort, shortness of breath and nausea occur more frequently in women. However, chest pain is the most common symptom in both men and women. ⁽³⁾ 

Change in heart rate during a heart attack

Effect on the heart during a heart attack

The heart is a vital muscle that pumps blood to the lungs so that it can receive oxygen. This blood then returns to the heart which pumps the blood to the rest of the body, as all cells require oxygen to function correctly. In a heart attack, ischaemia occurs when there is a restricted or complete blockage of blood flow to the heart. In other words, a portion of the heart is starved of oxygen, causing the cells in the heart to die. ⁽⁴⁾ Once the heart is starved of oxygen, cell death is not immediate; it can take between 20 minutes to several hours for this to occur. ⁽⁵⁾

A heart attack can lead to cardiac arrest. This is where the heart completely stops pumping blood around the body. This is an essential function of the heart as all our cells require oxygen. The body cannot survive for long once this happens, which is why CPR (cardiopulmonary resuscitation) is used to try and get the heart pumping again.

The most common cause of a heart attack is coronary heart disease. This is where the coronary arteries (vessels that supply blood to the heart) become blocked. The formation of coronary heart disease usually starts with ‘atherosclerosis’. This is a process where ‘bad’ cholesterol (low-density lipoprotein) accumulates in the blood, eventually forming fatty deposits (plaque), which start to line the inside of the artery. Over time the plaques can harden, which not only obstructs the blood from flowing through properly, but it reduces the elasticity of the vessel and can cause a rise in blood pressure. Sometimes, the hardened plaque can rupture, causing the body to start the clotting process. The resulting blood clot produced can either entirely or partially block the artery and cause a heart attack. ⁽¹⁾

Blood pressure during a heart attack

The heart rate refers to the number of times the heart beats in one minute and is measured in beats per minute (bpm). A resting heart rate differs among individuals depending on general health and other factors - however, it is usually in the range of 60 and 100 bpm. ⁽⁶⁾ When your heart rate becomes too low, it is termed ‘bradycardia’; when it is too high, it is called tachycardia. An electrical signal in the heart governs your heartbeat. The signal starts in a single location in the heart and eventually spreads across the whole heart, causing it to contract. This contraction is vital for the normal blood-pumping function of the heart. 

We can detect the heart's electrical activity using an Electrocardiogram, often called an ECG. Sensors are attached to the skin, and the electrical signals produced by the heart are picked up and recorded visually. The visual is known as a PQRST complex, and the shape of this complex can indicate whether the heartbeat is normal or whether there are irregularities. Therefore, doctors use an ECG to detect a heart attack and other conditions, such as arrhythmias (irregular heartbeats). 

The heart rate may change or stay the same during a heart attack. It depends on general health and whether any medication is already being taken to control the heart rate and blood pressure. Often the heart rate will increase as your heart rapidly tries to receive more blood and oxygen. ⁽⁷⁾

Overall you cannot use your heart rate as a guide to whether you have a heart attack. Although an abnormally fast or slow heart rate may be a reason to seek medical attention, it does not necessarily indicate a heart attack. 

Types of heart attack

There are three main types of heart attacks. To understand the different kinds of heart attacks, it may be helpful to know how the heart produces a heartbeat and what a ‘normal’ heartbeat looks like:

The heart consists of four chambers. The top two chambers are called the atria, and the bottom two chambers are called the ventricles. An electrical impulse is sent from the right atrium, which spreads and causes both atria to contract. This forces blood into the ventricles. The electrical impulse spreads around the bottom of the heart, causing the ventricles to contract and helping to push the blood outside the heart to other areas of the body. These contractions and relaxations make up the heartbeat and can be represented on the ECG as the PQRST complex. ⁽⁸⁾

In a heart attack, there will be changes to this ‘normal’ heartbeat. There are different forms: ⁽⁷⁾

STEMI (ST-segment elevation myocardial infarction)

• This is known as the ‘traditional’ heart attack and is also the most serious
• A coronary artery is completely blocked
• The heart rate tends to increase - however, due to medications such as beta-blockers or damage within the heart, the heart rate can also sometimes slow down.
• Symptoms include the primary five heart attack symptoms.

NSTEMI (non-ST segment elevation m myocardial infarction)

• A coronary artery is obstructed but not completely blocked, so there is reduced blood flow to the heart
• NSTEMIs can be further categorised depending on what causes the restricted blood supply
• Just like in a STEMI, the heart rate usually increases but can also decrease in some patients
• Symptoms typically include chest pain, dizziness, pain in the back, jaw or neck, sweating and nausea

Coronary spasm

• These occur when the muscle within a coronary artery constricts in such a way that the artery narrows. If you think of an artery as a hollow tube, less blood can flow through when the inside of this tube is made smaller. 
• The heart rate may be increased, or there may be slight changes in the heart rate.
• The symptoms usually come and go; often, each episode lasts for around 15 minutes. The symptoms include chest pain, nausea, sweating and lightheadedness. 

Treatment

The earlier the detection of a heart attack, the more likely the recovery will be successful. Initially, pain relief is offered in the form of morphine, and a spray called glyceryl trinitrate. This spray is used under the tongue to enter the bloodstream quickly. Aspirin is also given and is something that can be taken before entering the hospital to counteract any blood clots. It is best if the aspirin is chewed as this helps the drug enter the bloodstream as quickly as possible. ⁽⁹⁾

Upon hospitalisation, an additional antiplatelet drug may help blood flow. Percutaneous Coronary Intervention can also be performed; this is an emergency treatment that aims to widen the coronary artery in a coronary angioplasty procedure. A balloon is inserted into the artery and inflated to widen the vessel. Then a stent is used to keep the artery widened after the procedure. 

Sometimes, this may not always be possible, and a coronary artery bypass graft is performed. This involves removing a blood vessel from a different part of the body and attaching it to the coronary artery near the blockage. This gives the blood a new channel to travel and avoids the blocked area in the vessel. ⁽¹⁰⁾

Preventative measures are centred around diet and lifestyle. As heart blockages often occur due to a build-up of bad cholesterol (LDL)  - foods containing high levels of LDL should be avoided. These include: ⁽¹¹⁾

• Full-fat dairy products such as cheese and butter
• Red Meat
• Processed Meat
• Fried Food
• Sweets and Chocolates

As the heart is a muscle, it can be strengthened through regular exercise. Exercise also improves circulation and can help relieve and manage stress, which can be a risk factor when the stress is severe. 

Other medical conditions affecting the heart rate

Although the symptoms of a heart attack can be very pronounced, they aren’t purely specific to a heart attack and can indicate a different issue:

Atrial Fibrillation

This is where abnormal electrical impulses are fired from the top chambers in the heart (the atria). This will show up on an ECG as an altered P wave. The heart rate is irregular and fast (tachycardia). It can lead to blood clots in the heart if not treated. 

Atrial Flutter

Another condition causes an irregular heartbeat (arrhythmia) because the top two heart chambers (the atria) are contracting prematurely. 

Supraventricular tachycardia

The heartbeat is abnormally fast even when you are resting. It affects the heart's upper chambers and can last from a few minutes to a few days. Symptoms include chest pain, a pounding sensation in the neck and chest, shortness of breath and dizziness.

Ventricular Fibrillation

Ventricular fibrillation is a medical emergency. This condition stems from the heart's lower chambers (the ventricles). It is a form of arrhythmia brought about by the unnecessary twitching of the ventricles. Symptoms are similar to that of a heart attack and include a loss of consciousness. If it is not treated, it can lead to cardiac death.

Ventricular Tachycardia

When the lower chambers of the heart (ventricles) contract too fast, there isn’t enough time for blood to pool inside these chambers. This results in the body not receiving enough oxygen. Sometimes this can only last a few seconds and doesn’t cause any actual harm. However, sometimes, it may stay for longer and emergency medical attention should be sought in this case.⁽¹²⁾

Panic Attacks 

One condition that causes sweating, palpitations and a tightening of the chest is panic attacks. People who suffer from panic attacks often describe the event as traumatic; they may feel like their life is in danger, similar to a heart attack. Although heart attacks and panic attacks both involve chest pain, with panic attacks, the pain remains localised as opposed to in a heart attack, where the pain often radiates to other areas of the body, such as the arms and jaw. Unlike a heart attack, symptoms of a panic attack will usually subside after a few minutes. The shortness of breath is brought about because the panic attack triggers the heart to beat faster, called ‘tachycardia’. This can also make you feel lightheaded. ⁽¹³⁾

Summary

If you are around someone experiencing any warning signs or symptoms of a heart attack, do not hesitate to call the emergency services. While these symptoms may not be associated with a heart attack, they must still be addressed.