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Explained: A heart attack while exercising – why it happens and who is at risk

Comedian Raju Srivastava suffered a heart attack while working out in a gym. Does high-intensity exercise raise the risk of a heart attack? We explain

Comedian Raju Srivastava suffered a heart attack while working out in a gym. (File Photo)

Comedian Raju Srivastava suffered a heart attack on August 10 while working out in a gym. Over the years, there have been reports linking strenuous physical activity to sudden cardiac death. Does high-intensity exercise raise the risk of a heart attack?

What causes a heart attack?

Heart attacks are caused when there is a sudden blockage in the coronary arteries supplying blood to the heart muscle.

“Chronic obstruction of 70 per cent or more in a coronary artery produces angina or chest pain on exertion, since available blood supply does not meet the increased oxygen demand during exercise. However, a heart attack (acute myocardial infarction) can also occur when soft plaques that form in the coronary arteries rupture and cause a large clot to form. This may come without any prior warning symptoms. Even plaques of 30 per cent can rupture and lead to the formation of a large obstructive clot,” said Prof K Srinath Reddy, a cardiologist, epidemiologist, and president, Public Health Foundation of India (PHFI).

A common misconception is that a blockage results from deposits of fat (lipids, cholesterol) and cells on the artery wall — similar to blocks in household plumbing. This is incorrect, according to Dr Tushar Gore, managing director, Resonance Laboratories.

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“The blockages are a result of cells and cholesterol particles breaking through the barrier of endothelial cells and infiltrating the lining of the artery. As a result, there is a bump in the artery wall — like a pimple. This is known as plaque or stenosis. The plaque need not bulge into the artery but could protrude outwards as well… Break-up and disruption of such blockages inside the coronary artery initiates blood clotting mechanisms to ‘repair’ the injury from plaque disruption,” he says.

According to Dr Reddy, “Plaques form in the coronary arteries due to injury caused to the blood vessel lining by factors causing inflammation.”

Fats circulating in blood can then deposit at the site of injury to grow the plaque, says Dr Reddy.
High blood pressure, smoking, diabetes, unhealthy diets, stress, inadequate sleep or recent infection are factors that can cause such inflammation.

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“Each of those chronic causes of inflammation can also acutely precipitate a plaque rupture leading to a heart attack, if there is a sudden or severe rise in one or more of those factors,” Dr Reddy added.

What causes cardiac death during exercise?

Sudden cardiac death during strenuous physical activity occurs more often in cases where blockages are undiagnosed, and sometimes in the background of a known diagnosis.
Vigorous exercise can also cause plaque rupture or trigger electrical disturbances in the heart leading to cardiac arrest, Dr Reddy said.

Dr Suman Bhandari, Visiting Consultant, Interventional Cardiology, Fortis Escorts Heart Institute, says: “If a patient is revived in such a situation, he or she stands a better chance as compared to sudden cardiac arrest at rest where the heart is usually weak (heart failure).”

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This does not mean exercise is bad for the heart. “It is essential to detect and control the risk factors which build and rupture plaques in the coronary arteries. Care and caution are all the more needed in Indians who have an ethnic susceptibility to experiencing a heart attack at younger ages than other population groups,” says Dr Reddy.

Can diagnostic testing help?

To identify risk, three things need to be detected: presence of small plaque; likelihood of plaque disruption (known as vulnerability); and the clotting intensity of blood. Reliable non-invasive diagnostic tests are available only for the first — detection of small plaque. Nevertheless, testing (even if it were to be available) for each of these will not offer a guaranteed window into the future because all the three factors change depending on lifestyle and environmental conditions.

First published on: 18-08-2022 at 05:34:40 am
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