Heart Attack vs. Sudden Cardiac Arrest: Do You Know the Difference?

Q&A with Dr. Daniel Hermann, interventional cardiologist, Memorial Hermann Health System.

According to the Centers for Disease Control and Prevention (CDC), cardiovascular disease is the leading cause of death for men and women in the United States. There are roughly 800,000 heart attacks reported annually nationwide. Alongside these statistics, more than 350,000 out-of-hospital cardiac arrests occur each year in the U.S., with nearly 90% of them fatal.

That’s why cardiovascular disease still remains a growing public health concern. As an interventional cardiologist, often times, I hear the terms, heart attack and sudden cardiac arrest, used interchangeably. While they sound like the same thing, sudden cardiac arrest is different from a heart attack. Both conditions are caused by different problems. However, a heart attack can sometimes trigger an electrical disturbance in the heart that could lead to sudden cardiac arrest.

Understanding the difference between a heart attack and a sudden cardiac arrest is important so you know how to respond to these medical emergencies when minutes count.

What is the difference between a heart attack and sudden cardiac arrest?

The best way to differentiate these two heart conditions is to think of your heart as a house with a plumbing and electrical system. Just like a house, each system of your heart requires regular maintenance to prevent cardiac conditions, such as a blocked artery or an irregular heartbeat. When the heart’s plumbing system (veins and arteries) is clogged, your heart cannot circulate blood and oxygen throughout the body which can trigger a heart attack. If your heart’s electrical system is malfunctioning, like an irregular heartbeat, this could lead to sudden cardiac arrest.

A heart attack, also called a myocardial infarction, specifically refers to the severe narrowing of one or more of the arteries that limits blood flow to the heart muscle. A person can experience a heart attack as a result of that. A heart attack occurs when an artery supplying blood to the heart is blocked. Without blood flow, the heart muscle is starved of oxygen and the tissue loses oxygen and dies. The damage worsens the longer the artery stays blocked. The blockage is usually caused by a blood clot formed from the buildup of fatty deposits (cholesterol and plaque) in the arterial walls of the heart. A heart attack is the result of a circulatory problem in the heart.

Sudden cardiac arrest refers to the heart stopping abruptly due to an electrical malfunction. A heart attack can increase the risk of a sudden cardiac arrest. As a result of the interruption in blood flow to the heart muscle, the heart may go into an abnormal rhythm or stop beating completely. When the heart’s rhythm is disrupted completely, your heart cannot pump blood to the brain and other vital organs, causing a person to lose consciousness without warning. If not treated within minutes, the outcome can be fatal. Arrhythmia (irregular heartbeat), atrial fibrillation (AFib) and cardiomyopathy can cause sudden cardiac arrest. Cardiac arrest can also be caused by blood loss, lack of oxygen and low levels of potassium and magnesium.

What are the warning signs and symptoms that I should look out for?

People with sudden cardiac arrest collapse without warning because of a lack of blood flow to the brain. They lose consciousness immediately and stop breathing. Fainting is usually the first sign of cardiac arrest. Other symptoms include dizziness, a racing heartbeat, lightheadedness and shortness of breath. This can happen all at once before a person loses consciousness.

Heart attack symptoms are more varied than symptoms of sudden cardiac arrest. The most common symptoms of a heart attack are shortness of breath, chest tightness or pressure, sweating, nausea or vomiting, and upper body discomfort in the arms, back, neck and jaw.

Heart attack symptoms in women may differ or be less noticeable than those in men.

What should I do if someone has symptoms of a heart-related emergency?

Whether a person is having a heart attack or sudden cardiac arrest, call 911 immediately and begin cardiopulmonary resuscitation (CPR) while waiting for emergency medical responders to arrive. By performing CPR, you can significantly improve a person’s chance of survival.

In a sudden cardiac arrest situation, begin CPR immediately and, when available, use an automated external defibrillator (AED). This device delivers an electric shock to the heart to potentially stop an irregular heartbeat and allow a normal rhythm to resume. If two people are available, one should begin CPR immediately while the other calls 911 and finds an AED.

Sudden cardiac arrest and heart attack are considered the most time-sensitive emergencies where immediate care and treatment can make a big difference in the outcome for a person. The faster a patient receives medical attention, the better their chances of survival. The longer you wait to seek help, the more damage can occur to the heart tissue. Every second counts.

What are some ways to help prevent a heart attack and/or sudden cardiac arrest?

Many cardiac disorders can be inherited, including arrhythmias, congenital heart disease, and high blood cholesterol. While there are many factors that impact someone’s risk of having a heart attack or cardiac arrest, there are things you can do to improve your overall heart health.

Besides sticking to a healthy diet of lean proteins, vegetables and fruit, it is important to exercise regularly. Thirty minutes of moderate daily activity improves blood flow and heart strength. It’s also important to maintain a healthy weight. Excess weight can make your heart work harder.

Also, see your doctor regularly to make sure your cholesterol, blood sugar and blood pressure are within the normal range to reduce your risk of heart disease. If you have a heart condition or had a previous heart attack, follow your doctor’s guidance and be sure to take any prescribed medications for high cholesterol or high blood pressure, to ensure that your levels are in check.

Smoking is a known risk factor for cardiovascular disease. Studies have identified that quitting smoking can reduce your risk of heart attacks and death. The earlier you quit, the better for your heart.