Myocardial infarction - causes, symptoms, diagnosis, treatment

Acute myocardial infarction is the medical term for a heart attack. It occurs when blood flow to the heart is reduced or stopped altogether. This can happen when an artery becomes blocked or fatty deposits build up on its walls. This results in poor oxygen supply to the heart muscle. If blood flow is not restored quickly, the affected heart tissue dies. Myocardial infarction is one of the top three causes of death worldwide. More than 1.1 million people suffer a heart attack each year, and for many of them it is the onset of coronary heart disease. The WHO says that the average age of patients diagnosed with this condition has decreased by 5 to 8 years.

Some patients experience chest pain when a heart attack occurs, but others have no symptoms at all. It is extremely important to recognize the signs of an impending myocardial infarction, as it can be largely prevented or its effects reduced.

How to recognize a heart attack

The classic "image" of a person having a heart attack is a person clutching their chest and complaining of crushing chest pain. However, in real life, if a heart attack occurs, the symptoms can be more subtle. Recent studies show that almost half of all heart attacks were silent. People simply did not know about their critical condition. As a result of not seeking treatment, their risk of death increased several times. That is why you should go to the hospital as soon as possible if you suspect that you are having a heart attack, even if you do not experience characteristic symptoms.

Moreover, the symptoms of a heart attack can be unnoticeable, obvious or completely absent. Many patients complain of chest pain radiating to the arm, neck, shoulder blade, even jaw. The condition is accompanied by shortness of breath, dizziness and weakness. Regardless of the combination of symptoms, it is important to see a doctor as soon as possible. Time is of the essence for a person with a heart attack, because the condition can lead to irreversible consequences.

So, other symptoms of a heart attack can be described as follows:

• chills, the patient breaks out in a cold sweat;
• burning in the chest, pressure, squeezing in the chest, a feeling of fullness;
• a feeling of fainting;
• severe nausea, sometimes with vomiting.

It is noteworthy that men with a myocardial infarction more often complain of chest pain, and in women, such symptoms of myocardial infarction as "shortness of breath", darkening in the eyes, dizziness are common.

The mechanism of a heart attack

The heart pumps oxygen-rich blood to the rest of the body through a complex network of arteries. However, the arteries around the heart can become blocked, usually due to a blood clot and less often due to severe spasms and dissection. When this happens, the blood flow slows or is blocked.

Over time, the heart tissue, which is starved of oxygen, dies. Blood clots can form due to plaques in the arteries. Spasms can be caused by medications, drugs, emotional stress, hypothermia, smoking. Sometimes arterial dissection occurs spontaneously, for example, during pregnancy.

Who is at risk?

The risk of experiencing a major heart attack is high in men over 45 and women over 55 with a family history of heart disease. This risk is increased by such conditions and lifestyle factors as:

• smoking;
• high blood pressure;
• high levels of bad cholesterol;
• diabetes;
• obesity;
• a sedentary lifestyle.

In young people, it is worth adding a lack of physical activity to the list of risk factors. If you have any risk factors, it is important to have regular heart examinations with a specialist to ensure your heart is healthy. It is especially important to take preventive measures and get examined now that you know what a heart attack is. 

How is a heart attack diagnosed?

Patients who complain of pain in the chest, arm, jaw, as well as people who show specific symptoms such as fainting or disorientation, sudden sweating, nausea, strong heartbeat, it is important to quickly take them to the hospital for diagnosis. It is important not to waste precious minutes, as any delay can lead to irreversible consequences, including death.

At the appointment, the doctor first listens to the heart with a stethoscope, does an electrocardiogram (ECG). This important test measures the electrical activity of the heart. Each time the heart beats, it produces tiny electrical impulses. The ECG machine records these signals on paper, allowing the doctor to see how well the heart is functioning.

An ECG is a painless, non-invasive procedure that takes about 5 minutes. During the test, flat metal discs (electrodes) are attached to the patient's arms, legs, and chest. They are connected to a machine that records electrical impulses.

An ECG is important because it helps:

• confirm a heart attack;
• determine the type of heart attack;
• prescribe the most effective treatment.

90% of patients with myocardial infarction have arrhythmia. This condition is characterized by an abnormal rhythm - the abnormal heart beats too fast or too slow, or irregularly. This affects the flow of blood and oxygen to the heart and can lead to palpitations, chest pain, dizziness, fatigue, or shortness of breath.

Patients develop heart failure, which means our natural motor cannot pump blood through the blood vessels as effectively as before. This leads to swelling of the arms and legs. One of the dangers is a ruptured heart. This is a rare complication in which a weakened area develops in the heart muscle that can tear.

The patient may be confused, pale, or have a blue tint to the skin. These people are usually taken to the emergency cardiac care unit to begin treatment.

Blood tests can help show physiological changes. The damage to the heart from a heart attack causes certain proteins to slowly leak into the blood. If doctors suspect a patient is having a heart attack, they will take a blood sample to test for heart proteins known as cardiac markers. The most common marker is cardiac troponin. Troponin levels can confirm or exclude a heart attack, as well as determine the type of attack.

Heart attacks are classified by an ECG measurement known as the ST segment and the level of troponin in the blood. A heart attack is a form of acute coronary syndrome (ACS) in which there is a significant blockage of the arteries. Types of Myocardial Infarction:

• ST-segment elevation type (STEMI) is a heart attack in which there is a prolonged interruption of blood supply. This can cause extensive damage to the heart. It is diagnosed when certain changes appear on the ECG. Urgent treatment is needed to unblock the artery.
• Non-ST-segment elevation type (NSTEMI) is another type of heart attack in which there is a small loss of blood supply, causing localized damage. It is diagnosed when the ECG does not show the changes typical of ST-segment elevation type, but blood tests confirm the damage.
• In unstable angina, all the signs of a heart attack are present, but diagnostic tests may not show them. The blood supply to the heart is still severely restricted, and the patient is at high risk of a heart attack. 

Other diagnostic tests that may be done if a heart attack is suspected include:

• Echocardiogram: An echocardiogram uses ultrasound to create a picture of the inside and outside of the heart. It helps determine how well the heart is pumping and how well the patient’s valves are working.
• Coronary angiography or cardiac catheterization: This is a procedure that uses X-rays and a contrast agent to visualize the blood vessels of the heart. It helps determine if there are any blockages.
• Cardial CT scan: This is a highly detailed scan of the heart and its blood vessels, which can show if there is significant narrowing or hardening of the major coronary arteries.
• Cardiac MRI: The test uses a powerful magnetic field and computer processing to create a picture of the heart. It can show problems with blood flow in the arteries.
• Exercise stress tests: A stress test is used during physical activity to determine if your heart is getting enough blood flow.
• Nuclear cardiac scanning: This technique uses a radioactive dye injected into the patient's blood and a CT scan to identify areas of the heart that are not getting enough blood or are damaged.

Cardiologists classify myocardial infarction by several other parameters:

• by the severity of pain symptoms: typical, atypical (in the absence of symptoms);
• by frequency (for a specific patient): primary, recurrent, repeated;
• by the degree of tissue damage: micro, extensive;
• by the location of the lesions: left or right ventricle, interventricular septum, apex of the heart, combined.

The examination helps to make an accurate diagnosis and prescribe treatment.

Myocardial infarction treatment

Treatment of a heart attack involves, first of all, restoring blood flow to the affected heart muscle. In simple terms, you need to improve the blood supply. This can be done in different ways, from drug treatment to surgery. Doctors choose how to treat a patient based on his condition. Treatment of myocardial infarction will most likely include several of the following methods:

• Supplemental oxygen. Patients with breathing problems receive oxygen therapy. Oxygen is supplied to them through a mask. This treatment increases the amount of oxygen circulating in the blood and reduces the load on the heart.
• Drug therapy. The doctor may prescribe drugs that prevent blood clotting, dilate blood vessels, destroy blood clots and antiarrhythmic drugs. Beta blockers and statins are also prescribed.
• A procedure called percutaneous coronary intervention (PCI) or angioplasty can be performed to restore blood flow to the damaged heart muscle. Opening the artery with a catheter is crucial to restoring blood flow. The sooner this happens, the greater the chance of a good outcome. This is evidenced by the statistics of how long patients survive who received timely medical care. During PCI, a stent can be placed in the place of the blocked artery, which holds the artery open to prevent another blockage.
• Coronary artery bypass grafting. People with severe blockage of the coronary arteries undergo coronary artery bypass grafting. Doctors often refer to this as open-heart surgery or bypass surgery. It involves using a blood vessel from another part of the body to create a bypass for blood and deliver it to the heart muscle. Remember, if you are diagnosed with a heart attack, treatment must begin immediately.

Treatment is not all that is done after a heart attack. Cardiac rehabilitation is equally important. This is a program specifically designed to improve cardiovascular health after a heart attack. A comprehensive rehabilitation program will cover three aspects:

• Exercise to lose weight and control risk factors such as diabetes, high cholesterol, and high blood pressure.
• Diet and medication.
• Quitting smoking and managing stress, anxiety, and depression.

Some patients are advised to have periodic monitoring with Holter monitors. What is it? These are special devices that monitor the heart's function over a long period of time in everyday life.

Preventing a Heart Attack

Doctors recommend the following steps to prevent a heart attack:

• Get a medical checkup to rule out the possibility of clogged arteries and get treatment if necessary.
• Identify any risk factors, such as diabetes, high blood pressure, high cholesterol, obesity, and smoking.
• Work with your doctor to keep your risk factors under control.
• If your doctor has prescribed medication, take it regularly.
• Quit smoking. Smoking almost guarantees you will have heart disease or cancer for life.
• Make lifestyle changes, such as eating a healthy diet and exercising regularly.

A large British study that followed more than 10,000 employees for 12 years found that people who were stressed at work were 68% more likely to die from heart disease, have a heart attack, or experience angina. And working overtime for three to four hours a day was associated with a fivefold increase in the risk of heart disease, independent of other risk factors. So, even if you can’t give up stressful work, you should try to reduce stress. Take short breaks where possible and move. Schedule regular exercise for 20 minutes each time. Learn to relax outside of work. This can be beneficial for your overall health. In many situations, we cannot avoid a heart attack, but preventive measures will help prolong the health of our engine for many years.