What is a Myocardial Infarction
Myocardial infarction, also known as heart attack, is caused by a lack of blood supply to cardiac muscles due to a narrowing or obstruction of the coronary arteries. The non-perfused cardiac cells gradually get weakened and die, followed by the complete death of the whole heart muscle, if proper treatment is not given on time.
Major risk factors for the development of coronary artery spasms and atherosclerosis include lifestyle factors such as tobacco smoking, alcohol, lack of physical exercise, obesity, comorbidities, etc. which can be described in detail as follows.
Risk Factors of Myocardial Infarction
Age
It is highly evident that men are always at a higher risk than women at any given age before menopause. However, this incidence becomes equal after reaching the menopause in women due to the lowering of estrogen levels.
Moreover, old age undoubtedly increases the risk of this condition despite gender.
Family history
A positive family history of ischemic heart disease or Myocardial infarction, particularly in a first-degree relative such as father, brother, mother, sister has a higher incidence in causing this condition.
Genetics
The role of genes in the predisposition of Myocardial infarction has been significantly highlighted as a result of developed scientific analytical methods and gene coding techniques. So far, about 27 genetic variants which are related myocardial infarction have been identified.
E.g. 9p21 genomic locus with a gene content of CDKN2A & 2B.
Lifestyle Factors
Long-term exposure to tobacco smoke and second-hand smoking are known to have a big impact on Myocardial infarctions (36% of affected people)
Prolonged intake of higher amount of alcoholic drinks also has a potential to increase the risk of this condition depending on underlying comorbidities.
Furthermore, short-term exposure to gasses and fumes like Carbon monoxide, Nitrogen dioxide, and Sulfur dioxide as a result of air pollution are known to increase the risk of affected individuals.
Lack of physical exercises associated with obesity can also predispose the condition. In fact, a 10% reduction of the current weight of obese individuals is known to reduce the possible incidence of a Myocardial infarction by 10%.
Psychosocial factors such as low socioeconomic status, social isolation, negative emotions, psychological stress and shift work are also associated with a higher risk of Myocardial infarctions.
Pain zones in myocardial infarction. Dark red: most possible area, Light red: other possible areas
Comorbidities
- Diabetes mellitus either type 1 or 2
- Hypertension
- Hyperlipidemia or dyslipidemia (especially high low-density lipoprotein, low high-density lipoprotein, high triglycerides)
- Endometriosis in women under 40 years of age
- Obesity- A BMI (body mass index greater than 30 kg/m² or a waist circumference or waist-hip ratio more than desired)
Infections
According to latest research studies, several acute and chronic infections such as Chlamydophila pneumonia, Influenza, Helicobacter pylori, and Porphyromonas gingival are found to be associated with atherosclerosis and myocardial infarction.
Oral contraceptive pills
Women who are using combined oral contraceptive pills on a long-term basis are known to have an increased risk of getting a myocardial infarction, especially in the presence other triggering factors such as smoking, obesity, and alcohol.
What Causes a Myocardial Infarction
The major pathophysiology behind a myocardial infarction involves the complete blockage of coronary artery blood supply, caused by a rupture of an atherosclerotic plaque made up of cholesterol, calcium, fibrin, abnormal inflammatory cells and several other cellular metabolites. The solid, fibrous capsule overlying a plaque could rupture in an instant following high cholesterol levels, sudden emotional stress, extreme cold, etc.
This will ultimately lodge inside the lumen of an artery (like a pimple protruding into the lumen from the wall), causing a significant obstruction, depending on the size. Furthermore, this rupture can result in attraction and accumulation of platelets in the site of trauma, similar to what happens after a cut or laceration on the skin results in the triggering of the clotting cascade where the fibrin clot itself can act an obstructive component.
Myocardial infarctions can also occur following coronary artery spasms as a result of severe emotional stress, drug abuse with Cocaine or Amphetamine and exposure to extreme cold.
Image Courtesy:
“AMI pain front” By J. Heuser JHeuser – (based upon image :Gray1219.png from Gray’s Anatomy) (CC BY-SA 3.0) via Commons Wikimedia
“Blausen 0463 HeartAttack” By Blausen Medical Communications, Inc. (CC BY 3.0) via Commons Wikimedia
