How is myocardial infarction diagnosed, and what is its treatment?

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The electrocardiogram is the most straightforward, obvious and practical test to diagnose acute myocardial infarction during pain. However, if, for example, the patient has an angina attack and consults the doctor between discomfort and pain, the electrocardiogram may be expected. In these circumstances, Lidón specifies that specialists can perform other tests, such as stress tests, to see if changes in the electrocardiogram occur when the heart is subjected to stress.

The main diagnostic tests performed are:

  • Electrocardiogram

The actual test to diagnose acute infarction also allows for analysing its evolution. During the electrocardiogram, the patient is monitored at all times.

The test reveals a graphic representation of the electrical forces at work on the heart. During the cardiac cycle of pumping and filling, a pattern of changing electrical pulses accurately mirrors the heart’s action. This test is painless and is usually done with the patient stretched out and calm, except when it is done during a stress test.

The electrocardiogram only detects changes at the time the pain occurs. Subsequently, it is used only to confirm or rule out if damage to the heart has occurred.

Blood test

A blood test can detect the increase in the serum activity of certain enzymes released into the bloodstream due to the necrosis that occurs during the infarction.

To give this data certainty, the enzyme values ​​are taken by series during the first three days. The maximum values ​​of these enzymes show a slight correlation with the extent of necrosis, although other factors that influence their degree of activity must also be considered. Ultimately, this is a complex value calculation.

On the other hand, interesting prognostic parameters are also obtained, such as cholesterol levels, glucose levels ( diabetes increases the risk of heart disease) and thyroid hormones (an overactive thyroid can cause cardiac disorders).

stress test

It can be done on a stationary bike or a treadmill. In the test, the specialist will place electrodes on the patient’s body to continuously record the electrocardiogram and a tension cuff.

While the patient pedals or walks on the treadmill, the doctor supervising the test will observe the changes in blood pressure, pulse and electrocardiogram tracing, the test is completed in half an hour. It is abandoned if there are changes suggestive of disease in the observed parameters or if the patient cannot tolerate it physically due to exhaustion or difficulty breathing.

Isotopic studies

These studies are associated with the stress test and analyse the heart with isotopes. During exercise on a bicycle or treadmill, a small dose of a radioactive isotope is injected into the vein. Meanwhile, a particular device records a series of images of the locations of the isotope in the heart (the dark areas indicate the parts where the blood flow does not reach well).

The negative point of this test is that the isotopes do not give information about the specifically blocked artery. However, there are different modalities of isotopic examination:

Scintigraphy increases the sensitivity and specificity of the stress test in men.

Ventriculography makes it possible to quickly determine ventricular volumes and detect areas of abnormal mobility due to ischemia very useful for prognosis.

Scintigraphy can detect defects in the expansion or contraction of the heart wall, a sign that the arteries are not carrying enough oxygenated blood to the area.

Cardiac catheterisation and coronary angiography

It is the most appropriate technique to determine ischemic heart disease’s possible presence and extent.

Coronary angiography makes it possible to determine the location and degree of obstruction of the coronary artery lesions that may have occurred. However, it cannot be performed when the patient has coagulation disorders, heart failure or ventricular dysfunction.


As soon as the patient suspects that they have some of the symptoms already described, they should immediately notify the emergency services. Then they can take aspirin (it has an antiplatelet effect that inhibits the formation of clots in the arteries). “One of the problems derived from a heart attack is that a malignant arrhythmia occurs, and the patient dies,” explains Lidón. “If the health service is in front, the consequences may be minor because they can activate the action protocol in the event of a heart attack.”

According to the specialist, the electrocardiogram will mark the type of treatment. Thus, if an ST-elevation myocardial infarction occurs, doctors will activate all the mechanisms to open that artery as soon as possible. “If the infarction is not ST elevation, the doctor will have to study the coronary anatomy and the heart’s pumping capacity, decide whether to perform coronary angiography and act accordingly, either through the same catheter or surgery.

The specialist insists that whether the specialists perform a percutaneous coronary intervention or if they perform surgery, the patient must follow medical treatment for life. “These treatments are indicated to facilitate healing, reduce the work of the heart so that it can function properly and prevent new heart attacks. “Our goal is to control all cardiovascular risk factors to prevent coronary heart disease from continuing to progress and, if it does progress, to do so as slowly as possible.

In the hospital, patients can receive different types of treatments:

Oxygen is usually the first measure doctors take in the hospital and the ambulance itself.

Analgesics: When chest pain persists, morphine or similar drugs are administered to relieve it.

Beta-blockers: They prevent the stimulating effect of adrenaline on the heart. In this way, the heartbeat is slower and has less force, so the muscle needs less oxygen.

Thrombolytic: They dissolve clots that prevent blood flow. They must be administered within one hour of the onset of symptoms and up to approximately 4.5 hours to be effective.

Platelet antiaggregants: This type of drug, such as aspirin, prevents platelet aggregation in the formation of thrombi.

Calcium antagonists. They are calcium channel blockers. They prevent the entry of calcium into the cells of the myocardium. This reduces the tendency of the coronary arteries to narrow and makes it possible for the heart to work less, so its oxygen needs decrease. They also lower blood pressure.

Nitrates. They decrease the work of the heart. In the acute phase of a heart attack, they are usually used intravenously and sublingually.

Digital. They stimulate the heart to pump blood.

Other treatments:

Coronary bypass. The procedure involves selecting a section of a vein or artery from another part of the body to join the coronary artery above and below the blocked area. This creates a new route or bridge through which blood can flow to the heart muscle.

 Percutaneous coronary intervention. The goal is to open the lumen of the blocked artery. The specialist will determine the infarcted vessel with an initial angiography and subsequently perform a balloon angioplasty of the thrombosed segment, being able to implant a stent simultaneously. Sometimes they can remove the thrombus with an aspirator catheter.

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