Heart Attack: What Actually Happens and Why It's Often Preventable

A heart attack does not usually happen out of nowhere. In most cases, it's the final stage of a process that has been building for years, driven by risk factors that can be measured and often changed.

A sudden blockage of blood flow to part of the heart muscle (known as a heart attack, or myocardial infarction) starves that tissue of oxygen. Within minutes, the affected muscle begins to die.

A heart attack can strike suddenly, often without warning, but in most cases, it is actually the end point of a process that has been building inside the body for years.

What actually causes a heart attack?

Most heart attacks are related to coronary artery disease, where fatty material builds up within the arteries supplying the heart. This process is known as atherosclerosis. Over time, cholesterol-containing particles and other material accumulate within the artery wall, forming plaques.

A heart attack commonly occurs when the surface of one of these plaques ruptures or erodes. The body responds as though the artery has been injured and forms a blood clot over the area.

Why can a plaque suddenly become dangerous?

How much a plaque narrows an artery does not necessarily tell you how likely it is to trigger a heart attack.

Large deposits that contain a lot of calcium and narrow the artery significantly often cause symptoms, such as chest pain that comes on with exertion (stable angina), but these larger deposits can actually be fairly stable.

Smaller, softer deposits are often more dangerous. They have a large fatty core and only a thin covering (a fibrous cap), which makes them more vulnerable to the inflammation that weakens this covering. When one of these deposits bursts, its fatty core is exposed to the flowing blood, triggering a blood clot that can block the artery completely within minutes.

How much damage occurs depends on factors including:

• Which coronary artery is affected
• How much blood flow is blocked
• How long the blockage lasts
• How quickly treatment restores blood flow
• How much heart muscle is supplied by the affected artery

Rapid treatment matters because restoring blood flow limits the amount of heart muscle damaged.

What are the symptoms of a heart attack?

Common symptoms include:

• Chest pain, pressure, tightness or squeezing
• Pain spreading to one or both arms, the neck, jaw, back or stomach
• Shortness of breath
• Sweating
• Feeling sick or being sick
• Feeling light-headed

What's less well known is that heart attacks often show up differently, especially in women, older adults, and people with diabetes. Chest pain may be mild or missing entirely. Instead, someone might just have shortness of breath, tiredness, feeling sick, or discomfort in the jaw and arm.

Heart attacks can occasionally occur with few or no noticeable symptoms. This is known as a silent myocardial infarction and is more common in older adults and people with diabetes.

If you think you or someone else may be having a heart attack, call 999 immediately. Do not drive yourself to A&E.

What happens to the heart after a heart attack?

Heart muscle cannot repair itself. Once tissue dies, it's replaced with scar tissue, which cannot contract like healthy muscle. This means the remaining healthy muscle has to work harder to compensate.

Depending on how much muscle is affected (the size of the infarct), the effects can range from barely noticeable to a serious loss of pumping power, known as heart failure.

How is a heart attack treated?

One of the most important treatments for certain types of heart attack is primary percutaneous coronary intervention (PCI), commonly known as coronary angioplasty.

A catheter is guided into the blocked coronary artery and a small balloon is used to reopen it. A wire-mesh tube called a stent is usually inserted to help keep the artery open.

Medicines that reduce blood clotting and other treatments may also be required depending on the type of heart attack.

Modern treatment has greatly improved outcomes, but preventing the underlying cardiovascular disease remains preferable to treating a heart attack after it occurs.

What increases your risk of a heart attack?

Many of the major risk factors can be identified before a heart attack occurs.

Smoking

Smoking damages blood vessels, accelerates atherosclerosis and increases the tendency of blood to clot. Stopping smoking is therefore one of the most effective changes someone who smokes can make to reduce their cardiovascular risk.

High cholesterol

Raised levels of atherogenic cholesterol - particularly LDL and other non-HDL particles - contribute directly to the development of atherosclerotic plaques. Both how high your cholesterol is and how long it remains raised influence lifetime cardiovascular risk.

High blood pressure

Persistently high blood pressure places additional strain on artery walls and increases cardiovascular risk. Because high blood pressure often causes no symptoms, measuring it is the only reliable way to know whether yours is raised.

Diabetes and insulin resistance

Diabetes substantially increases cardiovascular risk. Persistently raised blood glucose can damage blood vessels, while diabetes frequently occurs alongside other cardiovascular risk factors including abnormal cholesterol levels, high blood pressure and excess visceral fat.

Inflammation

Inflammation plays an important role in atherosclerosis and in the processes that can make plaques unstable.

One marker used to assess low-level inflammatory activity is high-sensitivity C-reactive protein (hsCRP).

The JUPITER trial studied 17,802 people without known cardiovascular disease who had LDL cholesterol below 130 mg/dL but hsCRP of at least 2 mg/L. Treatment with rosuvastatin reduced major cardiovascular events by 44% compared with placebo. It also lowered LDL cholesterol by around 50% and hsCRP by 37%.

The trial therefore supports hsCRP as useful additional information when considering cardiovascular risk, but it does not show that inflammation should be considered independently of cholesterol and other established risk factors.

Check your heart attack risk factors with Bluecrest

A heart attack can occur suddenly, but many of the factors that contribute to it can be identified much earlier.

Bluecrest's Heart Disease & Stroke Risk Test checks key markers associated with cardiovascular risk, including blood pressure, cholesterol, diabetes risk and circulation, helping you build a clearer picture of the factors you can act on.

Your personalised Results Report highlights anything that may need closer attention and provides guidance on appropriate next steps.

Book your health check with Bluecrest now and get a clearer picture of the factors affecting your long-term cardiovascular health.

This article is for general health information purposes and does not constitute medical advice. If you have concerns about your cardiovascular health, please speak with a healthcare professional.