ST-Segment Elevation Myocardial Infarction (STEMI)

Last updated date: 27-Aug-2023

Originally Written in English

ST-Segment Elevation Myocardial Infarction (STEMI)


What is an ST-elevation myocardial infarction?

Acute myocardial infarction is the loss of myocardial cells caused by a long-term imbalance between perfusion and demand. The most common cause of ST-elevation myocardial infarction (STEMI) is full atherothrombotic blockage of a coronary artery. A heart attack is referred to medically as a myocardial infarction. An infarction is an obstruction of blood flow to the heart muscle, the myocardium. Because of the obstruction, the heart muscle dies.

An ST-elevation myocardial infarction (STEMI) is a more dangerous form of heart attack with a higher risk of significant complications and death. It derives its name from the fact that it mostly affects the lower chambers of the heart and alters how electrical current flows through them.

A STEMI is a kind of myocardial infarction that results in a specific pattern on an electrocardiogram (abbreviated either as ECG or EKG). This is a medical test that employs multiple sensors (typically 10) applied to your skin to detect electrical activity in your heart. This action is then exhibited on a paper readout or a digital display as a wave pattern. The various components of the wave are identified with letters beginning with P and ending with U.


Epidemiology of STEMI

Epidemiology of STEMI

Each year, an estimated 550,000 new heart attacks and 200,000 repeat heart attacks (meaning the person has already had one) occur in the United States. A STEMI was found in around 38% of persons who presented to the emergency room with acute coronary syndrome. That indicates that around 280,000 persons in the United States suffer from a STEMI each year.


What causes ST-Segment Elevation Myocardial Infarction?

Coronary artery

The most severe form of coronary artery disease, ST-segment elevation myocardial infarction (STEMI), is linked with significant morbidity and death. The majority of STEMI cases are caused by a complete thrombotic blockage caused by an atherosclerotic plaque in a coronary artery.

Acute myocardial infarction is the loss of myocardial cells caused by a long-term imbalance between perfusion and demand. The most common cause of ST-elevation myocardial infarction (STEMI) is full atherothrombotic blockage of a coronary artery.

A number of risk factors enhance the likelihood of having a heart attack. Some of those elements are under your control, while others are not.


Modifiable risk factors:

The elements over which you have the most influence are those related to your lifestyle. These are some examples:

  • Smoking and tobacco usage
  • Diet, including salt (blood pressure), sugar (diabetes), and fat consumption (cholesterol).
  • The level of physical activity you engage in.
  • Excessive alcohol consumption.
  • Substance abuse (especially stimulants like amphetamines, cocaine, or any other medications that affect your heart).


Nonmodifiable risk factors:

These elements are as follows:

  • Age. As you become older, your chances of having a heart attack increase.
  • Sex. Men's chance of having a heart attack increases beyond the age of 45. Women's chance of having a heart attack increases beyond the age of 50 or after menopause (whichever comes first).
  • Family history. Your risk increases dramatically if you have a parent or sibling who had a heart attack when you were your age or younger. It also includes having a father or brother who was diagnosed with heart disease before the age of 55, or a mother or sister who was diagnosed before the age of 65.
  • Genetic or congenital conditions. Certain medical diseases or disorders might raise your chances of having a heart attack. These diseases are beyond your control if you inherited them (genetic) or were born with them (congenital).


What is the difference between a STEMI, a non-STEMI heart attack and unstable angina?

coronary artery disease

The phrase "acute coronary syndrome" (ACS) refers to three different forms of coronary artery disease. Patients suffering from ACS may develop unstable angina or a heart attack (STEMI or non-STEMI). Chest discomfort or pressure (angina), shortness of breath (dyspnea), or dizziness are all common symptoms.

The ST-segment elevation is the defining feature of a STEMI. ST-segment elevation often signals a complete blockage of the affected coronary artery and that the heart muscle is presently dying. Non-STEMI heart attacks frequently feature a partially blocked artery, which does not cause as much heart muscle damage. While ECG readings can indicate NSTEMI, a blood test to search for a specific molecule, troponin, in your blood is typically required for diagnosis. When your heart muscle is damaged, those cells produce troponin into your bloodstream. If the blood test shows troponin but you do not have ST-segment elevation, you most likely suffered a non-ST-elevation heart attack, or NSTEMI.

Blood clots develop, disintegrate, and re-form in unstable angina but do not cause a permanent obstruction. When this happens, a person may have sporadic chest discomfort while resting.


What happens before and during a STEMI heart attack?

STEMI heart attack

Most heart attacks are caused by blockages in the arteries that feed blood to your heart muscle. Typically, the obstruction occurs as a result of plaque, a fatty, waxy accumulation that collects on the inside of your arteries. On the plaque deposits, a blood clot can develop, quickly blocking the artery and cutting off blood supply to the heart muscle.

Ischemia occurs when blood flow is partially or completely interrupted. This is the medical name for how your cells and tissues begin to die as a result of a lack of blood supply. The decrease of blood flow during a heart attack leads the muscle in your ventricles to begin to die. If too much heart muscle is damaged, your heart may be unable to provide enough blood to your body.

This results in cardiogenic shock, which is frequently lethal. In addition, ischemia of the heart muscle can cause ventricular tachycardia or ventricular fibrillation, which can lead to cardiac arrest (when your heart stops completely) and abrupt death. STEMIs are often more severe than other types of heart attacks. Within 30 days, between 2.5% and 10% of those who have one die.


What are the symptoms of STEMI?

STEMI Symptoms

Anyone who is at risk of having a heart attack should be on the lookout for any odd symptoms and seek medical assistance immediately if any are discovered. The symptoms might differ from person to person. Among the STEMI symptoms are:

  • Pain around the shoulder blades, arm, chest, jaw, left arm, or upper stomach
  • Sweating or feeling out of breath
  • Discomfort or tightness in the neck or arm
  • Indigestion, which is stomach and chest discomfort
  • Heartburn, which describes when you have an acidic taste in your mouth and upper chest discomfort
  • Nausea and vomiting
  • Fatigue or unexpected weariness
  • Dizziness
  • Increased or irregular heart rate

Women are less likely than males to report chest pain or indigestion-like symptoms. Women who have a heart attack may encounter the following symptoms in addition to those listed above:

  • Insomnia, exhaustion, or shortness of breath that began prior to the heart attack.
  • Back, shoulder, jaw, neck, arms, or abdominal pain that spreads (or radiates).
  • Vomiting and nausea


How is ST-Segment Elevation Myocardial Infarction diagnosed?

ST-Segment Elevation Myocardial

STEMI is diagnosed by a doctor based on a physical assessment of your symptoms as well as diagnostic testing. A provider can do a physical examination and a patient history evaluation after you're medically stable and able to answer questions (where the doctor asks you questions about your medical history and personal circumstances).

The following tests are used to confirm or rule out a heart attack diagnosis:


Electrocardiogram (ECG):

This technique, which displays electrical activity in the heart as a wave pattern, is critical in determining a STEMI. It is helpful to comprehend ST-elevation by first learning about two distinct wave sections:

  • QRS complex: This is the huge peak that occurs on a heart wave. When the ventricles push blood out of your heart, they generate this wave.
  • ST-segment: This is a brief portion that follows the QRS complex. Normally, there should be no electrical activity in that section, resulting in it being flat and returning to baseline.

When the ST segment rises, it frequently indicates a complete blockage of one of the heart's main supply arteries. When this occurs during a heart attack, it may indicate that the muscle of the ventricles is dying. This is essential information for healthcare personnel to have during a STEMI because it indicates that the heart muscle is dying. That also implies the reopening that artery and restoring blood flow as quickly as feasible may avoid irreversible damage or, at the very least, decrease the degree of the damage.

This is problematic since your heart's ventricles are the chambers that pump blood to your lungs and body. If the muscle in the ventricles is severely damaged, your heart will be unable to pump enough blood to maintain your body. That is why STEMIs are so deadly, and why restoring blood flow as soon as possible is crucial.

Your heart muscle cannot also rebuild or replace itself, so if it is deprived of blood for an extended period of time, the damage to that muscle may be irreversible. However, restoring blood flow rapidly may prevent lasting damage or at the very least reduce the degree of the injury.



Echocardiography is the most often utilized imaging diagnostic for suspected heart attacks. This test creates a picture of your heart, including its interior anatomy, using ultra-high-frequency sound waves. This is also portable and may be performed without requiring you to leave your hospital bed, making it very handy and quick in an emergency.

Other imaging studies may be performed if the EKG or other tests are inconclusive but there is still reason to suspect a heart attack. It is also feasible to use the following tests:

  • Computed tomography (CT) scan: This examination employs X-rays and computer processing to provide a very detailed, layer-by-layer image of the heart. This test is frequently performed with contrast or another type of chemical or dye added to your blood. This dye can reveal where blood is flowing and where it isn't, assisting in the diagnosis of any obstructions.
  • Magnetic resonance imaging (MRI): This test processes photos and creates high-resolution photographs of the heart using an incredibly strong magnet and a computer.


Lab testing:

When your heart cells are damaged, they produce a substance called troponin. A troponin test can assist confirm a heart attack, which is crucial because ST elevation can be caused by a variety of illnesses. Among these conditions are:

  • Cardiovascular or pericardial inflammation (the sac around the heart).
  • Heart issues are induced by a high level of stress or emotional strain (takotsubo cardiomyopathy, also known as broken heart syndrome).
  • Abnormal heartbeats (arrhythmias).
  • Imbalances in electrolytes.


How is ST-Segment Elevation Myocardial Infarction treated?

STEMI treatment

A STEMI must be treated as soon as possible. That is, the sooner the therapy, the higher the odds of a positive outcome. If your blood oxygen levels are low, therapy may involve supplementary oxygen. There are also various possible therapies for heart attacks, some of which may occur sequentially or concurrently.


Percutaneous coronary intervention (PCI):

This procedure is carried out by an interventional cardiologist who inserts a catheter-based device into a major blood artery (usually in your wrist or near your upper thigh). The catheter is then threaded up to your heart. When you arrive, the cardiologist will inject contrast ("dye") into your arteries to locate a blockage and may then inflate a balloon on the end of the catheter to clear the obstruction.

Because PCI is time-sensitive, hospitals set a "door-to-balloon time" objective for heart attack patients. This is the time it takes for a patient to get from entering the ER to having PCI, and the shorter the better. It is also feasible to insert a stent (a scaffold-like device at the site of the obstruction) during PCI. The stent will help keep the artery open and prevent another blockage from occurring.


Medical therapy:

Several drugs are usually used early in the treatment of a heart attack. They are as follows:

  • Fibrinolytic therapy. If PCI cannot be done within 120 minutes of the beginning of STEMI, this is an intravenous infusion of a medication that dissolves the blood clot, restoring blood flow.
  • Beta-blockers. These lower the force with which your heart pumps and moderate your heart rate. This impact assists the heart muscle in dealing with decreased blood flow, preventing abnormal heart beats, and reducing heart damage.
  • Statins. These drugs reduce cholesterol levels in the blood by inhibiting its synthesis in the liver. This is significant because cholesterol (particularly at higher levels) is responsible for the formation of plaque, which can clog arteries.
  • Aspirin and antiplatelet medications. These drugs aid in the reduction of blood clot development on plaque in the arteries and, if a stent is placed during PCI, on the metal surface of the stent itself.
  • Anticoagulants. These treatments, like antiplatelet pharmaceuticals and aspirin, interfere with clotting, but in a somewhat different way.
  • Nitroglycerin. This medicine has a high vasodilation impact, which means it causes your blood vessels to dilate. That is why it is so helpful in treating chest discomfort caused by blood vessel obstructions.
  • Pain medications. When the discomfort in the chest is severe, morphine or other powerful pain relievers may be prescribed. 


Coronary artery bypass grafting (CABG) surgery:

Severe obstructions in your heart's arteries may necessitate coronary artery bypass grafting (CABG, pronounced like "cabbage). During this surgery, a surgeon removes a blood artery from another part of your body and utilizes it to create a new blood vessel that avoids the obstruction. CABG is sometimes referred to as bypass surgery or open-heart surgery.


How to prevent STEMI?

STEMI Prevention

There are a number of things you may take to assist avoid a heart attack. One of the most crucial is to have an annual physical. One of the most essential strategies to detect issues early is to schedule an annual appointment with your primary care physician (often known as a checkup or wellness visit). High blood pressure and diabetes, for example, may not show symptoms until they are advanced, but a healthcare professional can readily detect them during an annual examination.

There are various more measures you may take, many of which your primary care physician can advise you on and give information for:

  • Keep a healthy weight.
  • Consume a well-balanced diet.
  • Get at least 150 minutes of moderate-intensity activity every week (or higher).
  • If you use tobacco, stop using it as soon as possible.
  • Take charge of your health, particularly illnesses such as high cholesterol, high blood pressure, and diabetes (this includes taking your medication regularly, not just when you remember).

However, because of unchangeable factors, such as your age and family history, avoiding a heart attack isn't always achievable. Even so, it may be able to postpone the onset of a heart attack. Recovering from a heart attack — or any sickness, for that matter — is also simpler when you're healthy.


Prognosis of STEMI

Prognosis of STEMI

The length of a hospital stay following a heart attack might vary depending on the circumstances. It is frequently determined by the severity of the attack as well as the treatments you got. The usual hospital stay varies from four days for PCI to seven days for CABG operation. As you obtain emergency care, your symptoms of a heart attack should improve. It is normal to feel weaker or exhausted for several days following a heart attack and after returning home.

Several variables influence the prognosis of a STEMI. The most crucial aspect is how much damage the STEMI has done to the heart muscle. That is why, if you suffer STEMI symptoms, you must seek medical assistance immediately. Your healthcare professional is the best person to inform you what to anticipate and what you can do to improve your situation.

You are more likely to suffer another heart attack if you have already had one. Rest and follow-up treatment will most likely be recommended by your healthcare professional to help lessen the likelihood of this happening. Some of the most common forms of follow-up care are:

  • Regular follow-up and diagnostic imaging. These appointments with your healthcare physician allow you to monitor your recovery, overall health, and any changes in your heart function.
  • Cardiac rehabilitation. This sort of therapy focuses on rehabilitating patients who have a history of heart disease. These programs frequently involve specialists from a variety of sectors, including as diet and nutrition, exercise physiology and physical training, and others, to assist you.

You should be able to resume most of your typical activities within a few weeks or months of returning home. However, if you had surgery or if your heart attack was serious, your recovery time will be extended. Your healthcare practitioner can tell you more about how long your recovery should take, what objectives you may set for yourself, and what you can do to assist yourself in recovering.

If your symptoms recur or change suddenly, get quick medical assistance, especially if they are indicators of a heart attack or another illness. The following are the primary symptoms to look out for:

  • Angina (chest discomfort) or pain radiating to your jaw, neck, back, arms, or belly.
  • Breathing difficulty.
  • Vomiting or nausea
  • Feeling dizzy, lightheaded, or passing out.
  • Sweating.
  • Palpitations of the heart



 Segment Elevation Myocardial Infarction

ST-elevation heart attacks are a hazardous and occasionally fatal illness. Fortunately, advances in medical knowledge have shown excellent treatments for this issue. This understanding is also constantly expanding, as new treatments, drugs, and approaches become accessible. That means your odds of receiving life-saving care and recovering — especially if you receive care immediately — have never been greater.

Early diagnosis and prompt reperfusion are the most effective approaches to lower the risk of post-STEMI sequelae and heart failure by limiting myocardial ischemia and infarct size. In patients with STEMI, primary percutaneous coronary intervention (PCI) has become the recommended reperfusion technique; if PCI cannot be done within 120 minutes of STEMI diagnosis, fibrinolysis treatment should be delivered to dissolve the occluding thrombus.

Losing weight and exercising will enhance your cardiovascular health. If you've just had a heart attack, see your doctor before beginning a new fitness regimen. It's also critical to quit smoking if you do. Quitting smoking reduces your chance of having a heart attack and improves both your heart and lung health. You should also avoid being in the presence of secondhand smoke.

Fortunately, there are several strategies to avoid problems and limit long-term health implications connected with this illness. Making adjustments to your food and lifestyle can not only help you recover after a heart attack, but it can also help you avoid having another one in the future.