Pictured: our intricate cardiovascular system as seen through a skeletal graphic.

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What causes heart attacks is the stoppage of blood flow through a coronary artery. The heart muscle that normally keeps pumping blood out to the body and the lungs becomes starved for oxygen. Without a steady supply of oxygenated blood, heart muscle tissue becomes damaged. If blood flow remains blocked for a long time, part of the muscle will start to die and be replaced by scar tissue.

The long-term effects can be serious. The heart may become so weak that you develop heart failure, a condition in which a weakened heart can’t pump well enough to properly supply the blood with healthy circulation.

A heart attack is a sudden event that is often years in the making. In most cases, what causes heart attacks is the gradual build-up of plaque in the arteries that supply blood to the heart muscle—a process known as atherosclerosis. These blood vessels are called the coronary arteries, and the presence of dangerous plaques in them is known as coronary artery disease (CAD). (See also “The Four Heart Problem Symptoms You Shouldn’t Ignore.”)

The plaques themselves are made up of cholesterol and other substances, including proteins, waste products, and white blood cells. So if your goal is to know how to keep heart healthy, you may want to start with reducing the formation of plaques in your arteries.

What Causes Heart Attacks: Problematical Plaque

The reason plaques are so dangerous is that they can grow along the artery walls and narrow the space through which blood can flow. Of even greater concern is that the plaques can also rupture. The contents inside can form a blood clot that can completely block the artery.

But if blood flow is restored quickly, the damage may not be significant enough to interfere with normal cardiac function in the future. Treatment for a heart attack often involves a procedure called percutaneous coronary intervention (PCI). In PCI, a catheter is threaded through an artery (usually starting in the thigh) up to the blocked artery.

At the site of the obstruction, a tiny balloon is inflated to squeeze the plaque against the sides of the artery to clear it out for improved blood flow. Sometimes a flexible mesh tube called a stent is placed at the site of the blockage to help keep the artery open.

Signs of heart attack can turn up in various parts of the body.

Other Heart Attack Risks

To understand what causes heart attacks when the problem isn’t CAD, you need to learn a little about a condition known as a coronary artery spasm. This spasm can occur in an artery that is affected by atherosclerosis, but it can also happen in an artery where there is no blockage.

The spasm can cut off blood flow through that artery in the same way a blood clot can halt circulation to the heart muscle. Smoking cigarettes, using such drugs as cocaine, and even stress are among what causes heart attacks attributed to coronary artery spasm.

Avoiding a Heart Attack

If you want a complete picture of how to keep heart healthy, talk with your doctor about your particular risks. In general, however, you should follow these steps to preserve your heart health and reduce your odds of having a heart attack:

• Stop smoking. Discuss medications and other products that may help you quit with your doctor, and remember that most people need to try a few times before they kick the habit for good.
• Maintain a healthy weight. If you are overweight or obese, talk with your healthcare provider about a target weight and the strategies to get there safely.
• Follow a heart-healthy diet, such as the Mediterranean-style eating plan or the Dietary Approaches to Stop Hypertension (DASH) diet. Dietary cholesterol may play a small role in the formation of cholesterol in your blood vessels, so keep foods high in saturated fat and cholesterol to a minimum. Click here for our post “Cardiac Diet: The Road to Wellness Starts Here.”
• Exercise every day. Aim for at least 150 minutes of moderate-intensity exercise (such as brisk walking) every week. But be sure to get up and move throughout the day. Exercise can help reduce plaque buildup in your arteries.
• Take a cholesterol-lowering drug, such as a statin, if your doctor recommends one. These are usually well-tolerated medications that can be very effective at lowering your heart attack risk.

Now that you know what causes heart attacks and how to keep your heart healthy, the rest is up to you. Make good lifestyle choices and follow the advice of your healthcare providers. Not all heart attacks are fatal, but they should always be taken seriously.

For further reading, see these University Health News posts:

• “Mild Heart Attack Symptoms: What Do They Mean?”
• “What You Should Know About Open-Heart Surgery”
• “Cardiac Arrest Symptoms: Know the Signs and Risk Factors“

Originally published in 2016 and regularly updated.