Enlarged hearts and arrhythmia associated with intense exercise can result in sudden cardiac death.

In June 2021, Christian Eriksen, Denmark’s midfielder, had a heart attack and collapsed during the Euro 2020 match against Finland. While the footballer survived thanks to a medical team who were able to revive him, other athletes have not been so lucky.

Despite the belief that sportspeople are the least likely to suffer cardiac events, sudden cardiac arrest (SCA) or abrupt loss of heart function, is the leading cause of sports-related death among athletes, resulting in 1 in 80,000 to 1 in 200,000 sudden cardiac deaths (SCD) per year globally.

In Singapore alone, 83 sports-related deaths were recorded between January 2005 and December 2015, of which 72 were caused by SCD.

Why do high-performance athletes with good health and fitness end up suffering cardiac arrets?

Dr Alvin Ng, Senior Consultant Cardiologist from Jireh Heart Centre, the Mount Elizabeth Novena Specialist Centre, puts it down to a condition known as athlete’s heart syndrome (AHS).

AHS is a constellation of structural and functional changes, including atrial fibrillation (a form of arrhythmia or irregular heartbeat) and hypertrophic cardiomyopathy (enlarged hearts) that occur in people who practise frequent, intensive cardiovascular training. Considered the most common serious heart conditions among athletes, atrial fibrillation is two to 10 times more likely in athletes who practice endurance exercise (such as running, cycling, or rowing) than sedentary individuals, while enlarged hearts affect up to 53 in 3,500 in young athletes below age 35.

“Athletes have an increased risk of hypertrophic cardiomyopathy because the heart receives more blood due to increased circulation during exercise. When you increase the capacity within the heart, it receives a direct pump of blood which stretches the left and right atria”, Dr Ng says.

“When the upper chambers of the heart stretch, they can prevent adequate blood from leaving the chamber, elevating risks of arrhythmia. Arrhythmia occurs when the electrical impulses that coordinate your heartbeats don’t work properly, triggering problems such as heart palpitations, chest pain, and sudden cardiac arrest and death,”.

In addition to structural and functional changes due to intense exercise, other factors which can also contribute to arrhythmia in athletes are lifestyle triggers such as alcohol or performance-enhancing drug use, as well as inherited heart conditions including Long QT Syndrome, Short QT Syndrome, Brugada Syndrome, or Wolff Parkinson White Syndrome.

How much exercise is too much?

According to a study of 44,000 Swedish men between the ages of 45 to 79, those who exercised more than five hours a week were 19% more likely to develop atrial fibrillation than those who exercised less than one hour per week. However, despite physical activity increasing the risk of arrhythmia, a sedentary lifestyle can, in contrast, contribute to cardiovascular disease, hypertension, diabetes, and obesity.

In Dr Ng’s opinion, the optimal level and amount of physical activity varies between patients, depending on their individual health condition and fitness level.

“Non-athletic individuals should aim for 10,000 steps a day. Otherwise, at least 30 minutes of daily exercise that raises your heart rate to 50% to 85% of your maximum heart rate (220 minus your age) can also improve one’s cardiovascular health. Nevertheless, while anything over 85% is considered overexertion in normal people, professional athletes regularly train above 100% of their target heart without problems, proving that the right amount of exercise is different for everyone,” Dr Ng says.

“And since everyone has different capacities to exercise, I suggest that patients simply slow down/stop your workouts as soon as you experience any discomfort including pain, breathlessness, heart palpitations or tightness of the chest during training,” he adds.

Dr Alvin Ng, Senior Consultant Cardiologist from Jireh Heart Centre

How is AHS treated and prevented?

In most cases, AHS management begins with conservative methods such as rest/activity modification. If athletes are unable to scale down their training due to professional commitments, Dr Ng may suggest surgical, and non-surgical treatments, or both to manage and control their symptoms.

“While a reduction in training can certainly improve AHS, this may not be well-received by athletes, particularly at the competitive level. For this reason, doctors may instead recommend anti-arrhythmic agents and/or surgical procedures such as pulmonary vein isolation surgery or a pacemaker to maintain normal heart rate and rhythm,” he says.

As for how the condition can be prevented, Dr Ng advises everyone (including non-professional athletes) to consult a doctor before embarking on any intense physical training.

“Unlike cuts or bruises, you cannot see or feel an enlarged heart. If athletes would like to embark on intense exercise while avoiding cardiac events, I suggest they visit a general practitioner or cardiologist who can not only conduct various exams to pinpoint any underlying heart problems, but also advise on the types and levels of exercises you can practice as to avoid any deadly consequences,” he says.


Featured image by Dreamstime.

Dr Alvin Ng photo courtesy of himself.

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