Acute myocardial infarction (IMA)

That is why it is important to correctly recognize the miocardic infarction, from the very first signs and to resort to emergency medical services.

What is acute myocardial infarction?

Because myocardial infarction is a complex condition that depends on various factors, cardiology experts worldwide have developed multiple definitions and classifications over time.

• ‍Acute myocardial infarction (AMI) essentially refers to the death of a portion of the heart muscle due to a lack of oxygen supply. This can occur due to blockage in one of the arteries that supplies blood to the heart or an inadequate supply of oxygen to the heart despite adequate blood flow.

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• Cardiac ischemia occurs when blood flow to the heart is insufficient, leading to a lack of oxygen supply to the heart muscle which contracts rhythmically without interruption. If the condition is not treated urgently, the affected areas of the heart begin to self-destruct, leading to myocardial necrosis.

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• As a result, cardiac biomarkers (cardiac troponins) are released into the blood, causing elevated values above the permissible limit. Additionally, myocardial ischemia manifests as specific symptoms and changes in the electrocardiogram (ECG) readings.

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Acute myocardial infarction is also known as acute coronary syndrome. Depending on the changes detected on the electrocardiogram, acute coronary syndrome can be classified as either ST segment elevation myocardial infarction (STEMI), which is associated with complete blockage of one of the heart's arteries, or non-ST segment elevation myocardial infarction (non-STEMI), which occurs when the artery supplying the heart is partially obstructed.

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Diagnosis of myocardial infarction

• The diagnosis of acute myocardial infarction is made in an emergency setting based on a physical examination and an electrocardiogram (ECG) test.

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• Laboratory tests are also performed to detect specific biomarkers for heart injury (cardiac troponins), as well as a complete coagulogram, blood count, ESR, and other tests as needed.

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• The electrocardiogram is an essential part of the diagnostic process for patients suspected of having myocardial infarction and should be performed as soon as possible after the onset of symptoms.
• Performing an electrocardiogram in the prehospital setting reduces diagnostic time and enables prompt treatment, helping to triage patients with ST-segment elevation myocardial infarction (STEMI) and direct them to hospitals with cardiac catheterization laboratories within the recommended time frame (120 minutes from STEMI diagnosis).

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Other investigations of patients with acute coronary syndrome include: determining blood pressure values, echocardiography, and coronary angiography for diagnostic and therapeutic purposes.

Coronary angiography:

• visualize the location of the obstruction,
• remove any thrombus,
• fit a special device (stent) to prevent the heart artery from being blocked.

Restoring blood flow to ischemic cardiac tissue as soon as possible within the first 4-6 hours from the onset of symptoms of myocardial infarction can prevent extensive tissue necrosis and shorten the patient's recovery period after the acute event.

Symptoms of acute myocardial infarction:

• Chest pain felt as a tightness or pressure (angina pectoris) with very high intensity lasting more than 20 minutes is a typical symptom of a heart attack. The pain may also radiate to the shoulder blade, the left arm, or the jaw. In certain situations, a heart attack may be accompanied by pain in other areas such as the upper abdomen or right arm, which can lead to an early diagnosis.
• Breathlessness (lack of air);
• Digestive symptoms: vomiting, nausea;
• Sweating,  pale skin;
• Anxiety;
• Tachycardia;
• Dizziness, 
• Syncope 

 Most cases of heart attack with complete obstruction of the heart artery and reduction of coronary blood flow (STEMI) are caused by the rupture of an atherosclerotic plaque in the vessel wall and the subsequent formation of an occlusive thrombus.

What is atheroma plaque? 

An atherosclerotic plaque is a buildup of fats (especially cholesterol) inside the arterial wall, forming plaques that can narrow the lumen of the blood vessel as they develop, creating blockages in the path of blood flow.

This damage to the blood vessels is known as atherosclerosis.

• Atherosclerosis is a slowly progressive disease that can begin in childhood and occur not only in the arteries of the heart or brain but also in any segment of the body.
• When this phenomenon occurs slowly over years, a collateral network of blood vessels develops adaptively in the heart to cope with its oxygen needs. Therefore, a myocardial infarction occurring in a younger person, who was not able to build up this network in time, may take more serious forms than in an older person.
• The high level of cholesterol in the blood, especially the LDL fraction, also called "bad cholesterol," is the main risk factor for the occurrence of atherosclerosis.
• Constantly elevated triglyceride values above the permissible limits also correlate with atherogenic risk.
• Those who smoke, have hypertension, are obese or sedentary are also at risk of developing atherosclerosis.
• Atheroma plaques, once formed in the arterial wall, grow and narrow the vessel, hindering blood circulation.
• Some of these plaques can rupture, leading to blood clots that can block the arteries, resulting in myocardial infarction, stroke, or necrosis in the limbs, which may require amputations.

Causes of myocardial infarction

• Thrombosis of one of the heart's arteries is the most common cause of myocardial infarction. It occurs, in most cases, in the background of atherosclerosis of the coronary arteries.
• The clot develops from "unstable" atheroma plaques susceptible to erosions, ulcers, and ruptures.  
• There are medicines that can prevent the appearance of atheroma plaques or establish existing ones so regular medical check-ups and a close connection with the family doctor and cardiology specialist is essential.
• Vascular inflammation plays a vital role in the instability of their atheroma plaques, favoring the appearance of acute coronary syndromes. 
• Thus, the circulating levels of inflammatory markers such as C-reactive protein (CRP) indicate the risk of major cardiovascular events.

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 Risk factors for myocardial infarction

A variety of factors associated with an unhealthy lifestyle increase the risk of cardiovascular disease and, consequently, the occurrence of acute myocardial infarction.

These factors include:

• being overweight or obese,
• leading a sedentary lifestyle,
• excessive alcohol consumption,
• diseases such as high blood pressure or diabetes mellitus.

Complications of myocardial infarction

In myocardial infarction, a smaller or more extensive portion of the heart is damaged, which can lead to complications depending on the affected blood vessel or its location in the heart.

The most common complications that can occur after an acute coronary syndrome are:

• arrhythmias (abnormal heart rhythms),
• heart failure,
• pericarditis,
• rupture of the heart muscle,
• valvulopathies,
• acute pulmonary edema.

These complications require urgent treatment, which may include medications, surgery, or other procedures such as stent placement.

Care of the patient with myocardial infarction.

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The most critical stage that can determine the survival of a patient with myocardial infarction is the onset phase when cardiac pain occurs.

The sooner the patient or those around them can recognize the symptoms and call the emergency service for early administration of myocardial revascularization therapy, the greater the benefit. In this phase, "time is muscle".

Unfortunately, precious hours are often lost until specialized medical assistance is requested, and during this time, necrosis of the myocardium spreads, which can lead to loss of life or serious sequelae.

The general public should be educated to recognize the symptoms of myocardial infarction and to intervene promptly, while those with ischemic heart disease should be aware of their risk of developing an acute coronary syndrome and know how to manage it if it occurs.

It is crucial to urgently call the ambulance service!

The pain associated with myocardial infarction can sometimes be atypical, and more pronounced digestive symptoms can mislead the patient, leading them to believe that it is indigestion.

It is important to note that the prolongation of the infarction can be stopped if the clot (thrombus) that has occluded the coronary artery, which brings blood to the heart muscle, is removed early. This method is known as myocardial reperfusion.

Mortality of patients with infarction can be greatly reduced, and the subsequent evolution can be clearly improved if the resumption of blood flow in the myocardium is performed within the first 4-6 hours from the onset of the acute cardiac event.

A healthy lifestyle, which takes into account nutrition, exercise regimen, normal body weight, sleep with adequate  duration  and control of all  cardiovascular risk factors, can prevent the occurrence of coronary heart disease and the way to myocardial infarction. 

 The following are required:

• Regular control of blood pressure
• Monitoring cholesterol levels and trigliceride
• Low-fat diet, rich in fiber and increased consumption of fruits and vegetables
• Controlling blood sugar levels in people with diabetes
• Increasing the number of hours allocated to physical activity
• Smoking cessation
• Better stress control