What's the difference between a heart attack, cardiac arrest and heart failure?

Cardiovascular diseases (CVDs) are disorders of the heart and blood vessels and are the leading cause of death around the world.

Almost 18 million people died from them in 2019, making up roughly a third of all deaths worldwide, according to the World Health Organization (WHO). More than three-quarters of these deaths take place in low and middle-income countries.

Cardiovascular disorders can lead to heart attack, cardiac arrest or heart failure – three terms that are often used interchangeably, but which are not the same thing. They have different causes and require different treatments.

A heart attack is caused by blood flow to the heart being blocked. This is commonly the result of a blood clot or because of plaque building up in the arteries.

If the blood flow to the heart becomes blocked, the heart muscles will start to die. This is why heart attack sufferers need urgent surgery to restore blood flow.

However, heart attacks aren’t always sudden events. The symptoms can start slowly. And not all symptoms are the same, with around two-thirds of sufferers experiencing chest pain, shortness of breath or tiredness for days or weeks beforehand, according to the Cedars-Sinai Medical Center in Los Angeles.

Cardiac arrest is caused by disruption to the heart’s rhythm, whereas a heart attack is linked to blood circulation issues.

Heart attacks are a common cause of cardiac arrest, but most heart attacks do not actually lead to cardiac arrest.

“During cardiac arrest, the heart cannot pump blood to the rest of the body, including the brain and lungs,” says the US Centers for Disease Control and Prevention. “Death can happen in minutes without treatment.”

Most cases of cardiac arrest happen when a heart’s electrical system malfunctions. This often happens during a medical emergency and “is not necessarily preceded by heart disease”, Cedars-Sinai says.

Heart failure can occur when the heart is unable to pump as much blood as the body needs. “Heart failure does not mean your heart has stopped working. It means it needs some support to help it work better,” says the UK’s National Health Service (NHS).

Heart failure is a long-term condition that tends to get gradually worse, the NHS says, which is why it is more common in older people – although it can happen at any age. “Symptoms can develop quickly (acute heart failure) or gradually over weeks or months (chronic heart failure),” the NHS adds. They can include breathlessness, excessive tiredness, fainting or feeling lightheaded, and swelling of the ankles and legs.

The long-term nature of heart failure means treatment is often needed for life. It will tend to limit the activities people are able to carry out, and is often eventually fatal, the NHS adds.

The WHO says that “most cardiovascular diseases can be prevented by addressing behavioural risk factors such as tobacco use, unhealthy diet and obesity, physical inactivity and harmful use of alcohol”. However it also notes that it is vital to detect CVDs as early as possible to increase the likelihood of successful treatment.

Global deaths from non-communicable diseases (NCDs) such as cardiovascular, and respiratory issues, cancer and diabetes exceed those from all communicable diseases, according to the World Economic Forum’s Global Health and Healthcare Strategic Outlook 2023: Shaping the Future of Health and Healthcare.

They account for 71% of deaths a year, representing 41 million people. And 29 million of these deaths occur in low or middle-income countries.

The Forum’s report says services for the prevention, education, screening and treatment of NCDs remain out of reach to billions of people living in rural areas in low or middle-income countries. However, relatively cost-effective services like eye tests can greatly contribute to the diagnosis of many disorders, including heart disease.

"Something as simple and non-invasive as an annual vision care exam is about so much more than seeing clearly," Michael Guyette, President and Chief Executive Officer of VSP Vision, told the report. "Through it, eye doctors can also detect signs of over 270 serious conditions, including diabetes and heart disease – sometimes even before symptoms appear. And when we can help catch these conditions early, we can empower patients and healthcare systems to reduce costs and improve overall health outcomes."