With a massive heart attack, a blocked artery prevents a large part of the heart from receiving oxygen. Quick treatment is essential when a person has a heart attack.

When the damage happens, it is hard for the heart to adequately pump oxygen-poor blood to the lungs and pump oxygen-rich blood to all of the body. With large heart attacks, there is also a risk of arrhythmias that can cause sudden cardiac death.

The most serious type of heart attack is an ST-segment elevation myocardial infarction (STEMI). It causes significant harm to the heart muscle because it stems from a complete blockage in blood flow rather than a partial blockage.

This article discusses what happens to someone during a massive heart attack and describes STEMIs. It also examines the signs, treatments, causes, and prevention of a heart attack, as well as when to call a doctor.

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A myocardial infarction is another name for a heart attack. This happens when a part of the heart muscle does not receive enough oxygen when something restricts or blocks blood flow.

There are different types of myocardial infarctions, one of which is STEMI. While all STEMIs are myocardial infarctions, not all myocardial infarctions are STEMIs.

Other types include non-ST segment elevation myocardial infarctions (NSTEMIs). This type does not have ST elevation on the electrocardiogram (EKG). Because there is still some blood flow, there is often less damage than in an STEMI. However, an NSTEMI is still serious and requires urgent diagnosis and management, often by a process that restores blood flow, called revascularization.

While heart attacks can stem from greatly reduced blood flow to the heart, the ones due to complete blockage of blood flow do the most damage, such as from STEMIs. This is especially true when the area of the blockage is in the proximal part of a main coronary artery.

The longer the delay in getting treatment after a heart attack, the greater the harm to the heart. Consequently, a delay in treatment can result in extensive damage that affects a large part of the heart muscle.

Read more about heart attacks here.

The heart muscle requires oxygen from the blood supply to survive. In a massive heart attack, a large part of the heart does not receive oxygen due to a blocked artery. Without quick treatment to restore blood flow, the part of the heart that normally gets blood from the now-blocked artery starts to die.

As a result, the heart cannot adequately perform its standard functions of pumping oxygen-poor blood out of the heart to the lungs and pumping oxygen-rich blood to all of the body.

Below are some of the effects that may occur:

  • serious arrhythmias or conduction disturbances, such as ventricular arrhythmias or heart block
  • swelling, discoloring, and coldness in the legs, ankles, and feet
  • wheezing or rattling sounds when breathing in if a buildup of fluid in the lungs occurs

STEMIs are the most serious type of heart attack. The name derives from an abnormal pattern on an EKG called an ST-segment elevation.

In an STEMI, a heart artery has a complete blockage, so an extensive part of the heart muscle cannot receive oxygen. This requires immediate treatment to open the blocked artery and restore blood flow.

Survival rate

Research from 2011–2018 reports that after adjusting for risk factors, 2.8% of people experiencing an STEMI did not survive their hospital stay.

Read more about STEMIs here.

Common warning signs of a heart attack include:

  • pain or discomfort in the chest that may feel like pressure or squeezing, and it may come and go.
  • nausea and vomiting
  • lightheadedness
  • shortness of breath
  • neck, jaw, or back pain
  • pain or discomfort in the arms or shoulders

Females and males may sometimes experience heart attacks differently, including females experiencing a “silent” heart attack more frequently.

Learn more about recognizing the signs of a heart attack here.

If someone experiences any warning signs, they should get medical attention immediately. Each minute of delay can make a difference.

Even when an individual is in doubt that their symptoms are due to a heart attack, they should call emergency services. This is the quickest way to receive proper treatment.

Whether the heart attack is an STEMI or NSTEMI, treatment may involve:

  • chewing aspirin immediately
  • getting oxygen therapy, if the oxygen saturation is low
  • receiving nitroglycerin under the tongue to relax the blood vessels
  • taking anticoagulants, such as heparin

Emergency treatment for an STEMI entails restoring the blood flow with percutaneous coronary intervention (PCI).

PCI is a minimally invasive procedure that opens clogged arteries. Before undergoing PCI, a person will take medication that helps prevent blood clotting. If a person arrives at a hospital that is not able to perform PCI, and there will be a significant delay, a doctor may use a thrombolytic agent, or clot buster, administered through a vein to restore blood flow.

The most common cause of a heart attack is coronary artery disease. This refers to the condition called atherosclerosis, where a coronary artery cannot carry enough oxygen-rich blood to the heart muscle due to the accumulation of plaque. This narrows the artery, and when the plaque breaks open, a blood clot forms that may block blood flow.

Other causes unrelated to atherosclerosis include:

  • Sudden, serious spasms of a coronary artery: Even when plaque has not accumulated, this can block blood flow. If a person smokes, they have a higher risk of having a spasm that stress or cold may trigger. Drugs, such as cocaine, may also cause spasms in a coronary artery.
  • Coronary artery embolism: This happens when a blood clot travels through the bloodstream, becomes stuck in a coronary artery, and blocks blood flow.
  • Spontaneous coronary artery dissection: This refers to a tear that forms in a coronary artery. When this happens, the torn tissue or a developing blood clot can block blood flow. Pregnancy, stress, or extreme physical activity can cause this.

According to the National Heart, Lung, and Blood Institute (NHLBI), the following healthy lifestyle practices can help prevent a heart attack:

  • engaging in regular exercise
  • eating a heart-healthy diet
  • quitting smoking
  • maintaining a moderate weight
  • managing stress

Additionally, getting treatment for conditions that raise the likelihood of a heart attack can help.

A massive heart attack may result from an ST-segment elevation myocardial infarction, especially since it involves a complete blockage in a proximal coronary artery supplying a large amount of heart tissue. Because of the loss of oxygen to the heart muscle, an STEMI can cause more extensive damage than an NSTEMI, which entails a partial blockage in a coronary artery.

Heart attacks have a high death rate, as most deaths occur before arriving at a hospital.

Common signs of a heart attack include chest pain that may feel like pressure or squeezing, as well as shortness of breath and lightheadedness.

Since death can happen within minutes after a heart attack, a person who experiences symptoms should call emergency services immediately.

Ways to prevent a heart attack include lifestyle measures, such as quitting smoking, exercising regularly, and eating a heart-healthy diet.