Causes of Heart Attack


risk factors of heart attack

Plaque is a substance which can gradually build up on the inner lining of the arteries, including coronary arties. This process is called atherosclerosis and it is the number one nemesis of humanity, with tumors and trauma taking the second and third places respectively. Plaque (also known as atheroma) is made up of a hard exterior shell made from calcium and a core made from cholesterol. These atheromas are formed in places where the inner lining of the arteries was damaged; therefore, it’s the body’s natural way of dealing with damage to the interior lining of the arteries.

  • Plaque gradually makes the arteries narrower; but usually that is not enough to cause a heart attack since the myocardial cells adjust to the gradual decrease in oxygen levels. Only when the artery is completely blocked by the plaque, can a heart attack occur.
  • The second, more common cause of a heart attack is when the outer shell of the plaque is damaged. This causes platelets to form a blood clot, quickly obstructing the blood flow. There is still debate as to what exactly causes the outer shell of the atheroma to become unstable and crack.

Less common causes of a heart attack

A number of other less common causes can result in a heart attack. They include:

  • Inflammation of the coronary arteries
  • A stab wound to the heart
  • Obstruction of the coronary arteries by a blood clot that was formed elsewhere. Usually such blood clots form in heart chambers and travel to the coronary arteries with the blood flow.
  • Cocaine can cause a spasm of coronary arteries resulting in a heart attack.

Risk factors

The majority of risk factors that increase the chances of a heart attack do so by increasing the extent of the atherosclerotic processes within the body. As mentioned before, atherosclerosis is our main enemy and here is the list of things which make us more susceptible to this condition:

    • Male gender. In an age group below 45 years old, men are three times more likely to suffer from a heart attack. The reason for this is that high levels of estrogen in female body guard the arteries from atherosclerosis. However, after menopause, when the levels of estrogens drop, the chances that a woman will have a heart attack sharply rise.
    • Tobacco smoking. Nicotine is a very large contributor to the formation of atherosclerosis. Therefore, despite the fact that electronic cigarettes are marketed as a “safe” alternative, if the solution for an electronic cigarette contains nicotine, it is just as harmful as a regular cigarette in respect to the formation of atherosclerosis. Therefore, the only upsides of electronic cigarettes are:

o   They don’t cause you to smell of tobacco;

o   They don’t cause cancer – which isn’t very likely in the first place, unlike the atherosclerosis.

  • High blood pressure. High blood pressure causes damage to the interior lining of the arteries. As mentioned above, atheromas are formed in places where the interior lining of the artery was damaged. Therefore, high blood pressure promotes the formation of atheromas. On the other hand, atherosclerosis itself contributes to increased blood pressure because, when the arteries of kidneys become obstructed by atherosclerosis it triggers them to release a hormone called renin which increases blood pressure. This is a natural response to keep an optimal blood pressure within the kidneys.
  • Obesity. People who are overweight have a much higher risk of atheroma formation than those who have a body weight index within 18-25 range. This is especially true for people who are predisposed to having more fat accumulate on their waist and abdomen (male-type fat distribution), rather than on their thighs (female-type fat distribution). The reason for this is that male-type fat distribution causes a person to accumulate a lot of visceral fat (fat located behind the abdominal wall). An excess of visceral fat causes a condition known as Metabolic Syndrome. Among other things, this syndrome is a large contributor to the formation of atherosclerosis Moreover, obesity is the number one contributor to higher blood pressure, and as mentioned previously, it can also cause atherosclerosis. Metabolic syndrome also causes the tissues to develop insulin resistance which can cause Type II diabetes.
  • Diabetes. The high content of sugar within the bloodstream causes glycosylation of proteins, including proteins located within the interior lining of arteries. This damage to the arteries results in formation of plaque. As well, diabetes Type I and II are large contributors to obesity and high blood pressure which creates a downward spiral.
  • Cholesterol. High levels of cholesterol contribute to the formation of plaque (which is partially made from cholesterol). Lowering the blood levels of cholesterol can cause atheromas to decrease in size; however, it cannot eliminate them completely, since the outer shell of atheromas is made from hard calcium. Obesity (Metabolic syndrome) and diabetes contribute to higher levels on blood cholesterol. Latest studies have shown that dietary cholesterol does not increase the levels of “bad” cholesterol within the bloodstream.
  • Inactivity and diet. Not having enough daily exercise and eating more calories than you burn per day contribute to obesity and therefore to atherosclerosis.
  • Family history. People are much more likely to develop atherosclerosis and consequently suffer from a heart attack if they have close relatives who have had a heart attack below the age of 55.


Next Chapter: Symptoms of Heart Attack




To learn more about Cardiology, we recommend the following websites: