STEMI

An ST-segment elevation myocardial infarction (STEMI) is a type of heart attack that happens when one of your coronary arteries is totally blocked. Such a blockage stops blood flow to your lower heart chambers (ventricles) and affects their electrical activity. This makes a distinct pattern on an electrocardiogram (ECG/EKG) graph, which is how this condition got its name.

STEMIs have a greater risk of serious complications and death than heart attacks that result from a partial blockage (NSTEMI). But you can’t tell the difference based on how you feel. And a partial blockage can quickly turn into a total one. All heart attacks are medical emergencies.

Call 911 (or your local emergency service number) right away if you think you’re having a heart attack or have any early warning signs. Every minute matters. Delays in seeking care can lead to permanent heart damage or death.

STEMIs are common and affect hundreds of thousands of people in the U.S. each year. Even though more people survive than in the past, STEMIs are still a leading cause of death globally.

Types of STEMI

Healthcare providers name STEMIs based on which coronary artery is blocked. You might hear them say:

• Anterior STEMI: This usually happens when there’s a blockage in your left anterior descending (LAD) artery, which provides blood flow to the anterior (front) side of your heart. Because this artery feeds so much of your heart muscle, this kind of STEMI can cause a lot of damage. It’s sometimes called a “widowmaker.”
• Inferior or lateral STEMI: These result from blockages in the right coronary artery (RCA) or the left circumflex (LCX) artery. The RCA supplies the inferior (bottom) side of your heart. The LCX artery supplies the side wall of your heart. Because these arteries supply less heart muscle than the LAD, these STEMIs are slightly less severe than an anterior STEMI.

Symptoms of STEMI

STEMI symptoms are the same as those for any type of heart attack and include:

• Chest pain or discomfort
• Pain that spreads to your jaw, neck, shoulder, arm or back
• Shortness of breath or trouble breathing
• Feeling very tired or weak
• Upset stomach, nausea or vomiting
• Anxiety or feeling like something bad will happen
• Sweating a lot
• Feeling dizzy or lightheaded
• Passing out

Seek emergency care immediately if you have these symptoms. Call 911 or your local emergency services number. Never drive yourself or let someone else drive you.

This is because first responders can start caring for you in the ambulance. They can also share information with healthcare providers at the hospital before you arrive. This saves time and lets you get lifesaving care as quickly as possible.

STEMI causes

A STEMI happens when a blood clot completely blocks blood flow in one of your heart’s arteries. The clot typically forms over plaque — a mix of fat and other stuff — that breaks open or wears down inside the artery. This type of complete blockage is the most severe form of coronary artery disease.

Risk factors

Your risk for a STEMI, or any type of heart attack, goes up if you:

• Smoke or use other tobacco products
• Regularly eat foods high in sodium, saturated fat and/or sugar
• Don’t get enough physical activity
• Have high blood pressure or chronic kidney disease
• Consume too much alcohol
• Use certain addictive substances, like amphetamines or cocaine
• Have a history of premature coronary artery disease in your biological family (before age 55 in males or age 65 in females)

Complications of a STEMI

A STEMI prevents oxygen-rich blood from nourishing your heart muscle. The longer the blockage lasts, the more damage it can cause. Areas of your heart muscle may start to die.

Possible complications include:

• Abnormal heart rhythms, like atrial fibrillation and ventricular arrhythmias
• Blood clots in your lower left chamber (left ventricular thrombus)
• Heart walls, muscles or valves coming apart (heart rupture)
• Lack of blood flow to the rest of your body (cardiogenic shock)

How doctors diagnose this condition

STEMI diagnosis begins as soon as first responders reach you. They’ll check your vital signs and do an EKG — a test that shows how your heart is beating. If the EKG shows a pattern called “ST-segment elevation,” it usually means one of your coronary arteries is totally blocked. That means your heart muscle is getting damaged and needs treatment fast.

Other tests that help providers diagnose a STEMI and its complications include:

• Blood test: Checks for elevated troponin levels (a sign of heart muscle damage)
• Echocardiogram (echo): Uses sound waves to look at your heart
• Cardiac CT or MRI: Takes detailed pictures of your heart

Providers also review your medical history and may ask about your symptoms if you’re able to speak.

How is a STEMI treated?

The goal of STEMI treatment is to get blood flowing to your heart again as soon as possible. This usually involves having a procedure called percutaneous coronary intervention (PCI) to open your coronary artery. You’ll also need medications to help your heart work better and lower your risk of complications.

Treatments to restore blood flow include:

• Percutaneous coronary intervention (PCI): Your provider inserts a thin tube into a blood vessel in your arm or thigh. The tube carries a tiny balloon to your blocked artery. Your provider inflates the balloon to open your artery and usually places a stent to keep it open.
• Fibrinolytic therapy: In certain situations where PCI isn’t possible, healthcare providers use medicine to break up blood clots. They give it through an IV line or catheter and watch you closely.
• Coronary artery bypass grafting (CABG): This is surgery to craft a new blood vessel that gets around the blockage. It’s not usually a first treatment for STEMIs, but you may need it if you have severe blockages or complications. 

Medicines you may need include:

• Dual antiplatelet therapy: This means you take both aspirin and a P2Y12 inhibitor. These drugs help keep blood clots from forming on plaque in your arteries. They also lower the risk of clots forming on your stent after PCI.
• Anticoagulants: These also lower your risk of blood clots but work in a different way than antiplatelet drugs.
• Statins: These block the production of cholesterol in your liver to lower the amount in your blood. This is important because cholesterol forms plaque that can clog arteries.
• Beta-blockers: These reduce how hard your heart pumps and slow your heart rate. As a result, your heart can better handle a reduced blood supply. These drugs also prevent irregular heart rhythms and reduce damage to your heart.
• ACE inhibitors or ARBs: These manage risk factors for heart attacks and strokes. They improve your chances of survival.
• Nitroglycerin: This relieves chest pain.

You’ll start taking these in the hospital. Your provider will adjust your doses as needed. They’ll tell you exactly which medicines you need to keep taking at home, and why.

Recovery time

STEMI symptoms should decrease as you receive emergency care. How long you stay in the hospital depends on the treatments you need and your overall condition. Most people go home within a week or two. It’s common to feel weak or tired for several days after you return home. You should gradually regain your strength and return to your usual activities over the next two to three months.

Cardiac rehab is an important part of your recovery. During this 12-week program, providers help you with exercise, nutrition and more. This strengthens your heart and lowers your risk of more issues down the road.

When should I see my healthcare provider?

Your healthcare provider will schedule regular follow-up visits with you. These start during your recovery and continue for the rest of your life. Once you’ve had a STEMI, you have a greater risk of having another heart attack. That’s why follow-ups are vital.

Call your provider any time you have new symptoms or just feel different than usual.

If chest discomfort or other STEMI symptoms return, call 911 or your local emergency services number.

What is the outlook for a STEMI?

Your outlook depends on many things. The most important factor is how much damage there is to your heart muscle from the STEMI. That’s why it’s so critical that you seek medical care quickly if you think you’re having a heart attack.

The good news: Treatments have come a long way. Many people live long lives after a STEMI — sometimes, even longer than people who haven’t had one. One study showed that those who survive 90 days after their STEMI have a good chance of living at least 10 years longer. 

The risk of death within 10 years of a STEMI goes up if you:

• Are female
• Smoke
• Have diabetes, high blood pressure or heart failure
• Have multiple co-occurring conditions

You can improve your chances of survival by:

• Taking your medicines exactly as prescribed
• Managing risk factors and other conditions
• Seeing your doctor for routine checkups and follow-ups