Cardiovascular link to sudden death during exercise

It seems unthinkable for someone who is fit, active, and healthy to collapse mid-run or during a sports game. Yet each year, this nightmare strikes a small number of people. 

However, experts warn that exercise isn’t the cause, and people shouldn’t become hysterical because it happens to a very small number of people. 

“If you’re looking at the entire population that exercises; the amount of life gained through practice and exercise; and the quality of life, if you look at the gain in those terms, and then you look at the small number of people that die during exercise, the pros far outweigh the cons,” said Wayne Derman, specialist sports medicine and exercise physician. 

“Every time somebody dies during or after exercise, it’s a catastrophic thing, and it triggers an emotional response, but that doesn’t mean that exercise isn’t good for you,” said David Jankelow, clinical cardiologist and president of the South African Heart Association. 

“Exercise is protective, but the point is that when people die from exercise who are below the age of 35, it’s usually due to a condition called hypertrophic cardiomyopathy where there’s inappropriate thickening of the heart muscle. There may be other congenital inherited or acquired issues with respect to the electrical system of the heart, which is difficult to elucidate.” 

For those above the age of 35, it’s usually due to coronary artery disease – a narrowing of the heart arteries. “But exercise is still protective, and if you look at the death rate of marathons, it’s low. But unfortunately, from time to time, it happens,” Jankelow said. 

Derman reiterated that this phenomenon, called “sudden death during exercise”, is rare and no cause for alarm. “Most of the causes of sudden death associated with exercise are related to cardiovascular conditions. And when we look at cardiovascular conditions, there’s a very clear demarcation in age,” he said. 

For those under the age of 35, death in these circumstances is mostly as a result of structural cardiac conditions, Derman said. These are congenital abnormalities that one has had since birth or has inherited, and are often unavoidable. “So, for example, there would be something called hypertrophic obstructive cardiomyopathy. These are conditions where the heart muscle itself is abnormal,” said Derman “There are also groups of conditions where there are abnormalities in coronary arteries, where they run abnormally in the wall of the heart rather than on the outside of the wall. And there are conditions where there are abnormalities with the iron channels in the heart that cause electrical problems. It would be those groups of conditions that cause a sudden cardiac death.” 

Derman said that for those over 35, sudden death during exercise is mostly attributed to coronary artery disease, in which the arteries that supply blood to the heart muscle – the coronary arteries – become narrowed or blocked. This reduces blood flow to the heart. 

Similarly, Jankelow said symptoms such as chest pain with exercise would be of concern. “That’s angina, which is due to blocked arteries,” he said. 

Jankelow suggests that those older than 35 should be screened to ensure that they are healthy. “How far you go is difficult. It depends on symptoms, history, and family history,” he said. “A family history of sudden cardiac death, particularly at a young age, is worrying. Those individuals might need extensive investigation. But a middle-aged athlete should be screened, have a basic examination, and at least an electrocardiogram (ECG).” 

Hatzolah paramedic Avigdor Hack said the Hatzolah ECG project, in which the organisation takes ECGs of every high school child at Jewish schools to look for abnormalities that could lead to sudden cardiac death in adolescence, has led to more than 2 000 ECGs and found three children with abnormalities that needed intervention. 

Derman said a point of concern for those under the age of 35 is viral myocarditis, inflammation of the heart muscle (myocardium) caused by a viral infection such as influenza. It can affect the heart’s ability to pump blood, and sometimes leads to serious complications, including heart failure, arrhythmias, or sudden death. 

To prevent these kinds of issues, Hack said, the most important thing is that people avoid exercising when they are sick. “There are so many different things that could cause your heart to stop when you’re doing exercise. The best way to prevent it is not to exercise when you’re sick,” he said. 

Derman said the most important thing was not to ignore symptoms. “People who have either abnormal heart rate during exercise or palpitations, or have any form of chest pain, dizziness, or breathing abnormalities, should get that checked out to see if there are any of these underlying causes that can be determined,” he said. 

“It depends on the patient’s history,” Jankelow said. “First, how are they feeling? Any shortness of breath, chest pain with exertion, or dizziness is concerning. Risk factors like smoking, high blood pressure, high cholesterol, or diabetes can indicate a higher chance of blocked vessels. Family history is also crucial. Sudden death in a first-degree relative may suggest a genetic issue, and warrants further investigation.”