Non-ST-Elevation Myocardial Infarction (NSTEMI)

Non-ST-elevation myocardial infarction, or NSTEMI, is a heart attack in which the ECG does not show a raised ST segment. The ECG may show a lowered ST segment or inverted T waves, or may even look normal. The diagnosis is made from a rise in troponin, a heart muscle protein that is released into the blood when heart cells are damaged. NSTEMI is a type of acute coronary syndrome and is now found more often than STEMI, especially in older adults.

Differences from STEMI and Unstable Angina

In STEMI, the artery is usually completely blocked, so it must be opened within hours, covered on the ST-Elevation Myocardial Infarction (STEMI) page. In NSTEMI, the blockage is usually partial or has closed briefly and then reopened, so blood still flows but not enough. In some patients with NSTEMI, the artery turns out to be completely blocked, especially arteries on the back of the heart that are less visible on the ECG. If the symptoms are similar but troponin does not rise, the condition is called unstable angina, covered on the Unstable Angina page.

Deciding the Timing of Treatment

Not every patient with NSTEMI needs catheterization within minutes. The ESC 2023 guideline groups patients by risk. Patients at very high risk, for example with ongoing chest pain, falling blood pressure, dangerous rhythm disturbances, or acute heart failure, are advised to undergo immediate coronary angiography, within 2 hours. Patients with a confirmed NSTEMI diagnosis are considered high risk and are generally advised to undergo angiography within 24 hours. The angiography results determine whether the artery is opened with a stent, treated with bypass surgery, or managed with medicines alone.

Long-Term Recovery

People with NSTEMI are often older and also have other conditions, such as diabetes, hypertension, or kidney disease. For this reason, their long-term risk is not lower than with STEMI. Antiplatelet medicines, statins, risk factor control, and cardiac rehabilitation are important parts of recovery. Before you go home, the doctor will explain the medicines you need to take, the warning signs to watch for, and your next follow-up appointment. An overview of all types of heart attack is covered on the Myocardial Infarction / Heart Attack page.

If you arrive with chest pain, an ECG is recorded within 10 minutes. If there is no ST-segment elevation, the doctor checks high-sensitivity cardiac troponin on arrival and repeats it 1 to 2 hours later, following the 0/1-hour or 0/2-hour algorithm in the ESC guideline. A rise or fall in troponin levels above the normal limit, together with symptoms or ECG changes, confirms NSTEMI.

Once the diagnosis is confirmed, the doctor assesses the level of risk, including with the GRACE score, to decide when coronary angiography should be done. Echocardiography assesses the heart's pumping strength and wall motion. If troponin is raised but the cause is still unclear, cardiac MRI can help distinguish a heart attack from myocarditis or Takotsubo cardiomyopathy. The doctor also rules out other causes of raised troponin, such as pulmonary embolism, heart failure, or severe infection.

Call an ambulance (119) right away or go to the nearest emergency room if chest pain or pressure lasts more than 5 minutes, occurs at rest, or becomes more frequent over a few days. Without testing, NSTEMI cannot be told apart from STEMI, so do not wait for the symptoms to ease.

After you return home from the hospital, contact your cardiologist or bring your follow-up visit forward if:

• Brief chest pain returns during activity.
• You become more short of breath, your legs swell, or your weight rises quickly.
• You have palpitations, dizziness, or nearly faint.
• You notice bruising, bleeding gums, black stools, or other unusual bleeding.