Sudden cardiac arrest (SCA) is a sudden loss of heart function. It is caused by a problem in the heart’s electrical system. The heart beats dangerously fast or stops beating and fails to pump blood to the rest of the body. SCA is different from a heart attack, which involves a blockage in a blood vessel to the heart.
What is Sudden Cardiac Arrest?
Sudden cardiac arrest (SCA) happens when the heart beats dangerously fast or suddenly stops beating. This is a medical emergency and can progress quickly to sudden cardiac death (SCD). If you suspect someone is in sudden cardiac arrest, call 911 and start CPR right away.
When playing sports, an athlete’s heart is working faster and pumping harder. Adrenaline is pumped throughout the body, and the heart needs more oxygen than normal. Dehydration, fever or changes in electrolytes (minerals in the body) can also play a part.
In people whose hearts are not normal to begin with, these extra stresses can sometimes trigger the electrical system of the heart at exactly the wrong time and cause sudden cardiac arrest.
While rare, SCA is the leading medical cause of death in young athletes. Use this condition center to learn more about sports and sudden cardiac arrest.
Signs and Symptoms
More than half the time, sudden cardiac arrest in athletes happens without warning. In these cases, the heart stops beating and the person collapses.
You can tell when someone is in SCA because the individual stops breathing, and no pulse is felt in the neck or wrist (no heartbeat). This is a medical emergency that requires action at once. Call 911 right away and start CPR right away.
When there are warning signs, the person can experience:
- sudden irregular heartbeat
- lightheadedness or dizziness
- chest pain
- shortness of breath
- prior episodes of passing out
If you have these symptoms, either with or without exercise, or if you have a family member who suffered an SCA, talk to your health care professional before continuing to exercise or play sports.
Exercise has many good effects on the body. For a small number of people, though, it can cause harm. This is because during exercise higher levels of adrenaline and stress affect your body. Your heart requires more oxygen to function. Also, there may be dehydration and electrolyte problems. If you have a normal heart, you can adjust to these changes. But physical activity can sometimes trigger an abnormal heart rhythm if you have certain types of heart disease.
Exercise may be risky for people who are born with certain heart conditions. In people younger than 35 years old, a genetic heart disease is a common cause of SCA. In these cases, people are born with a mutation in a gene that increases the chances of SCA. Some of these include:
- heart muscle disorders, such as hypertrophic cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy
- heart rhythm disorders, such as Wolff-Parkinson-White syndrome, Long QT syndrome, or catecholaminergic polymorphic ventricular tachycardia
Other conditions that increase your risk of SCA:
- being born with an abnormal heart artery
- heart infections
- Marfan syndrome, when the aorta — the main artery of the heart — ruptures
These conditions affect either the electrical or mechanical structure of the heart and may go undetected until sudden cardiac arrest happens. Electrical problems can stop the heart’s contractions. Mechanical problems can prevent blood from leaving the heart so not enough flows to the body and this may lead to an electrical problem. Both kinds of problems may give warning signs such as a racing heart, shortness of breath, chest pain or fainting with exercise.
In athletes older than 35, coronary artery disease is the most common heart condition to be a cause of SCA. But even in people with coronary artery disease, exercise can be safe.
For people with coronary artery disease, there are important benefits to exercise. Physical training lowers blood pressure and helps control diabetes and cholesterol.
Also, taking part in cardiac rehabilitation, an exercise-based program, after a heart attack lowers the chances of another heart attack. During exercise, if you feel chest pain, shortness of breath or dizziness, be sure to contact your physician.
Exercise is a good thing, but it’s important to talk to your doctor before starting an exercise regimen if you have heart disease.
Exams and Tests
Your health care professional will ask you questions about your symptoms and family history. To know if your symptoms are normal or not, it’s important to consider what sports and exercises you do, how long you’ve been doing them, and your exercise intensity.
You should find out if anyone in your family died suddenly, especially at a young age. It’s important to know if you or any of your relatives had episodes of passing out for no reason, drowning, car accidents, or seizures. These all may have been due to a heart condition.
Typically, your physician will obtain a thorough personal and family medical history and perform a physical exam. Long-term endurance athletes may have a slow pulse. Your health care professional also may listen closely to your heart for any murmurs.
Depending on your history and exam findings, she may recommend other diagnostic tests. The goal of these tests is to identify and treat the problems that might increase your risk of sudden cardiac arrest. Common tests include:
- Electrocardiogram (ECG). Your ECG should be interpreted with the knowledge that you are an athlete. People who exercise a lot, especially when young, may have an ECG that would look abnormal if you were a non-athlete.
- Echocardiogram (echo). An echocardiogram, or ultrasound of the heart . This test doesn’t hurt and shows the size and function of the heart. It can also look at the heart valves. For a more detailed look at your heart, your doctor may order a cardiac MRI (magnetic resonance imaging).
- Home ECG Monitor. If your heartbeat has been fast or irregular or if you have passed out, your doctor may want you to wear an ECG monitor at home. This may be for only one day or up to 30 days, depending on how often you have your symptoms. Some of these monitors are called Holter monitors and some are called event monitors.
- Stress Test. If symptoms occur during exercise, you may undergo a stress test when you run on a treadmill attached to an ECG. This can mimic the exercise that triggers your symptoms. Sometimes your doctor may also want to do this test using an echocardiogram or a nuclear medicine image. Another test may be a coronary calcium score. Interestingly, higher levels of exercise increase the amount of calcium and plaques in the arteries of the heart, but people in this situation are less likely to have a heart attack.
Genetic Testing may be recommended in specific cases. This requires either a cheek swab or blood work.
In rare cases, your doctor may do an electrophysiology study (EPS) to find out whether you have an issue with your heartbeat.
Playing Sports If You Are at Increased Risk
Health benefits of exercise are well known and proven. Exercise lowers cholesterol levels, aids in regulating blood sugar, helps with depression, supports a healthy weight and prolongs life. But exercise may be riskier for some than for others. If you are diagnosed with a heart condition, you should talk to your doctor about how best to go back to exercising.
In the past, patients with heart conditions were automatically told not to play sports. In recent years, research has shown that many people with heart conditions can participate in sports, with very low risk, under the right circumstances. You and your doctor will decide on the intensity of your sports participation and how closely you should be monitored. There may be recommendations about staying well hydrated, avoiding a fever, and watching electrolytes.
On your part, be sure to take the medications prescribed by your doctor. If you are an athlete with heart disease who has chosen to continue, with your doctor’s guidance, it is important to have a plan in place should an emergency occur. You should choose sports venues that are equipped to provide the best possible care if a medical emergency does arise.
We all have seen news articles about people dying suddenly during sports, but for many people with heart conditions, it can be OK to play again. Talk to your doctor about what is best for you.