The news of comedian Raju Srivastava suffering a heart attack while working out in a gym on August 10 adds credence to several reports that link strenuous physical activity to sudden cardiac death.
CAUSES OF A HEART ATTACK
Heart attacks are caused by a sudden blockage in the coronary arteries that supply blood to the heart muscle.
Cardiologist and epidemiologist, Prof K Srinath Reddy told The Indian Express: “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 Reddy, also president of the Public Health Foundation of India.
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A common misconception is the belief that a blockage is caused by fat (lipids and cholesterol) deposits and cells on the artery wall. However, Resonance Laboratories Managing Director Dr Tushar Gore said this was an incorrect idea.
“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 told The Indian Express.
Dr Reddy added: “Plaques form in the coronary arteries due to injury caused to the blood vessel lining by factors causing inflammation.” Fats circulating in the blood can deposit at the site of injury and grow the plaque, he said.
Smoking, high blood pressure, diabetes, stress, unhealthy diets, inadequate sleep or recent infection can cause such inflammation.
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Dr Reddy said: “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.”
REASONS BEHIND CARDIAC DEATH DURING EXERCISE
During strenuous physical activity, sudden cardiac death is often noticed in cases with undiagnosed blockages. Dr Reddy said vigorous exercise could also lead to plaque rupture or trigger electrical disturbances in the heart and lead to cardiac arrest.
Fortis Escorts Heart Institute Visiting Consultant (Interventional Cardiology) Dr Suman Bhandari told The Indian Express: “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).”
That doesn’t mean exercise is harmful for the heart. Dr Reddy said: “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.”
DIAGNOSTIC TESTING
Three things need to be detected to identify the risk: presence of small plaque, plaque disruption likelihood (known as vulnerability), and blood clotting intensity.
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Non-invasive diagnostic tests are available and reliable only for the first. However, testing for each of these will not offer a guaranteed timeline into the future as all the three factors change depending on environmental conditions and lifestyle.
