Dr. Samuel Aznaurov on Arrhythmias and Sudden Cardiac Arrest in Athletes

In part one of the two-part online Boulder Community Health lecture, “Recognizing and Treating Heart Problems in Athletes,” cardiologist Molly Ware, MD, spoke about how athletes’ demanding workouts can sometimes trigger physiological changes in the heart that can intensify an undetected heart problem. In part two of this lecture, cardiac electrophysiologist Samuel Aznaurov, MD, addressed arrhythmias (irregular heartbeats), syncope (unexplained and temporary loss of consciousness) and sudden cardiac arrest in athletes.

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VIDEO: Watch "Recognizing and Treating Heart Problems in Athletes."

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Dr. Aznaurov started his presentation by explaining, “Arrhythmias and syncope are things that we need to be aware of in those, such as athletes, who are pushing their hearts.” He described the following:

• Arrhythmias occur when the electrical impulses that coordinate your heartbeats aren’t working properly. This causes your heart to beat too quickly, too slowly or irregularly. A heart arrhythmia may feel like a fluttering or racing heart.
• Syncope is a sudden, often unexplained and temporary loss of consciousness. “Syncope can be a presenting symptom of arrythmia,” said Dr. Aznaurov.

The most common symptoms of syncope include:

• Blacking out
• Feeling lightheaded
• Falling for no reason
• Feeling dizzy
• Feeling drowsy or groggy
• Fainting, especially after eating or exercising
• Feeling unsteady or weak when standing
• Changes in vision, such as seeing spots or having tunnel vision
• Headaches

Types of Syncope

There are two types of syncope: benign and malignant. “Individuals who have experienced syncope need a workup for us to understand whether their case is benign or malignant,” said Dr. Aznaurov.

Benign Syncope

Benign syncope is the most common type. It is caused by a sudden drop in blood pressure that in turn causes a drop in blood flow to the brain. "This is similar to the woozy feeling that you may have experienced when you stood up too quickly,” Dr. Aznaurov explained. “It can occur with a sudden change in posture or from prolonged standing.”

While this may set off an inappropriate feedback loop, it’s normal. What happens, explained Dr. Aznaurov, is that we experience:

• Slowed heart rate
• Decreased heart pumping action
• Dilation of blood vessels

Dr. Aznaurov stated, “These conditions can be exacerbated by dehydration, medications, heat or situational factors, all of which point us in the direction of this likely being a benign event.” He added, “While these events are dramatic, they are not likely dangerous.”

Malignant Syncope

Malignant syncope may arise from the presentation of life-threatening illness such as an underlying cardiac or neurologic condition. Dr. Aznaurov said that most can be successfully treated, but they must be diagnosed and managed in a timely manner.

Features of malignant syncope that require medical evaluation include:

• If it was the result of an injury.
• If you lost consciousness when you were completely at rest or during peak exercise.
• If you needed chest compressions, CPR or lifesaving defibrillation when you lost consciousness.
• If you were unconscious for several minutes.

He stated, “A nontraumatic syncope—that is, one not resulting from concussion or injury — can be the main presenting symptom of arrhythmia. And, exercise-related syncope always requires investigation because it may be the only symptom that precedes a sudden cardiac death.”

Cardiac Arrhythmia and Sudden Cardiac Arrest

Congenital arrhythmia syndromes can cause sudden cardiac arrest. They tend to be associated with a family history of sudden death. There are some conditions that result from an inherited structural abnormality. They include:

• Hypertrophic cardiomyopathy (HCM) - HCM is a genetic disease that causes the heart muscle to become abnormally thick and stiffen. This makes it harder for the heart to pump blood. It often goes undiagnosed because people with the condition may have no symptoms. However, the thickened heart muscle can cause problems in the heart's electrical system, resulting in life-threatening abnormal arrhythmias or sudden death. Although deaths from sudden cardiac arrest are rare, HCM is thought to prompt 30 to 40 percent of sudden deaths in young athletes.
• Arrhythmogenic (right) ventricular cardiomyopathy (ARVC) – As a genetic condition, ARVC is an issue with the proteins that bind the heart's muscle cells together. This results in accelerated “wear and tear” of the muscle, causing the heart’s ventricles (lower pumping chambers) to become thin. ARVC can affect the electrical activity of the heart, leading to dangerous arrhythmias. About 20 percent of sudden death in young athletes result from ARVC. “If you carry the gene for this disorder and don’t exercise much, you will be safer than if you do exercise. This is very uncommon in the general population, less common in women, but very overrepresented in the population of athletes who experience sudden death,” said Dr. Aznaurov.
• Anomalous Coronary Artery – This is a much more common condition, half are typically benign. It occurs when the aorta causes a pinch in the artery and that pinch impedes blood flow, which can also cause arrhythmia. “However,” Dr. Aznaurov notes, “it’s responsible for 10 to 15 percent of sudden death occurrences in young athletes.”

• ION Channel Disorders –These are predispositions toward cardiac arrest in a structurally normal heart with mutations involving cardiac ion channels. There are three major categories: potassium, calcium and sodium channel disorders. Dr. Aznaurov noted, “All are extremely rare. Your risk does however increase if you have a family history of this disorder.”

Atrial Fibrillation in Athletes

“The much more likely arrhythmia that athletes experience is atrial fibrillation, or AFib” said Dr. Aznaurov. “This is a disorganized rhythm in the atria, the non-pumping chamber of the heart," he explained. “Athletes ask a lot of their heart and have a much higher risk of AFib than the general population because of the wear and tear they place on their heart,” said Dr. Aznaurov.

In fact, atrial fibrillation is present in about 15 percent of masters athletes. “In younger athletes, the risk factor may be related to a history of intense exercise. The highest risk group is middle-aged men with a history of more than 10 years of strenuous exercise,” he said.

Immediate effects of AFib include:

• Elevated heart rate
• Palpitations, fatigue, lightheadedness
• Exacerbation of underlying heart and/or lung conditions

In the long term, it can result in stroke or heart failure. Factors include:

• Age
• Cardiac disease – hypertension, diabetes, heart failure, valvular disease
• Non-cardiac disease – lung disease, sleep apnea, thyroid, anemia, alcohol/drug use and other issues

“It’s a progressive and a very individual disease. This means that treatments aren’t one-size-fits-all.”

Detecting — or Ruling Out — Heart Disease in Athletes

Make an appointment with a Boulder Heart cardiologist if you’re an athlete and experience any of the following symptoms:

• Fainting
• Chest pain or pressure
• Unusual shortness of breath
• Unusual heart racing/skipping
• Unexplained decline in exercise tolerance

Boulder Heart uses the latest heart technologies to diagnose potential heart problems in athletes, including imaging and stress tests. They can also evaluate whether your symptoms are related to physical activity or something more serious.

To make an appointment with a Boulder Heart cardiologist, call (303) 442-2395.

Click here to view/download a PDF of slides shown during this lecture.