Myocardial infarction

It consists of the death of cardiac tissue (myocardium) due to obstruction by various causes of the coronary arteries that supply it with oxygen. It is currently estimated to have an age-standardized incidence of 276 cases per 100,000 individuals, and is the leading cause of death and disability in the general population.

Acute temporary occlusion of one or more coronary arteries that supply blood and nutrients to the heart can lead to acute myocardial infarction due to lack of oxygen supply (ischemia). Depending on the territory affected, cardiac function will be more or less compromised. This arterial occlusion may have different origins.

  • Most heart attacks are triggered by the rupture of cholesterol deposits or plaques in the walls of the arteries which progressively narrow the diameter of the arteries, known as atherosclerosis. During a heart attack, a plaque can rupture and spill cholesterol and other substances into the bloodstream, forming a clot at the site of the rupture that can block blood flow.
  • This blockage of the coronary arteries can also be caused by an air bubble (embolism) that becomes trapped in a coronary artery.
  • Another triggering cause is a spasm or contraction of the coronary arteries that closes off blood flow in part of the heart muscle. Smoking or substance abuse can cause a life-threatening spasm.

Family history of myocardial infarction, especially at early risk ages (before 55 or 65 years of age for men and women respectively) represents a relevant genetic factor for myocardial infarction, however, there are other factors that contribute to the appearance of some of these causes:

  • Age. Men from 45 years of age and women from 55 years of age.
  • Tobacco use and long-term exposure to passive smoking.
  • High blood pressure since it can damage the coronary arteries. When accompanied by obesity, high cholesterol or diabetes, known as metabolic syndrome, the risk increases even more.
  • High levels of total cholesterol or LDL or triglycerides increase the risk of infarction, while high levels of HDL would reduce it.
  • Obesity is related to high blood cholesterol, high triglycerides, high blood pressure and diabetes.
  • Having both type I and type II diabetes increases the risk of having a heart attack.
  • An inactive lifestyle contributes to high blood cholesterol, obesity and even high blood pressure.
  • Stress.
  • Use of illegal stimulant drugs such as cocaine or amphetamines can cause coronary artery spasm.

Symptoms

Not all people who have heart attacks have the same symptoms or with the same severity; some even have no symptoms at all. In addition, although the heart attack may be sudden at times, it is often associated with warning signs and symptoms in the hours, days or weeks prior. The following are the most common symptoms of myocardial infarction:

  • Intense pressure, fullness, tightness, pain or discomfort in the center of the chest lasting more than a few minutes, which may spread to the shoulders, neck, arms or jaw.
  • Chest pain that worsens or does not improve with rest, and may be accompanied by sweating, cold and clammy skin, pallor, shortness of breath, nausea or vomiting, dizziness or fainting, unexplained weakness or fatigue, rapid or irregular pulse.

Although chest pain is the main sign, it can also be confused with other conditions such as indigestion, pleurisy, pneumonia, or heartburn.

Prevention

Reducing or limiting risk factors can delay the time of myocardial infarction and reduce the severity if it does occur:

  • Quit smoking. Smoking damages and narrows blood vessels, increasing the risk of coronary heart disease. Avoid passive smoking.
  • Eat a diet low in fat, cholesterol, salt and sugars, including fruits, vegetables, fish and omega-3 fatty acids.
  • Lose weight, exercise regularly and maintain an active lifestyle.
  • Limit alcohol intake.
  • Avoid stress.
  • Periodically control and prevent high blood pressure, high cholesterol levels and diabetes.

Number of observed variants

13.5 million variants

Number of risk loci analyzed in the study

89 loci

Bibliography

Shah ASV et al. Clinical burden, risk factor impact and outcomes following myocardial infarction and stroke: A 25-year individual patient level linkage study. Lancet Reg Health Eur. 2021;7:100141.

Johns Hopkins Medicine Institute. Heart Attack [April 2022]

Ojha N et al. Myocardial Infarction [April 2022]

Hartiala JA et al. Genome-wide analysis identifies novel susceptibility loci for myocardial infarction. European Heart Journal. 2021 Mar;42(9):919-933.

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