What are the 5 types of Non-ST-Elevation Myocardial Infarction (NSTEMI)?

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Last updated: April 11, 2025 • View editorial policy

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From the Guidelines

The 5 types of NSTEMI are Type 1, Type 2, Type 3, Type 4 (with subtypes 4a and 4b), and Type 5, as classified by the universal definition of myocardial infarction 1.

Classification of NSTEMI

The classification of NSTEMI is based on the underlying pathophysiology and is crucial for guiding treatment approaches. The types of NSTEMI include:

  • Type 1: Spontaneous myocardial infarction related to atherosclerotic plaque rupture, ulceration, fissuring, erosion, or dissection with resulting intraluminal thrombus in one or more of the coronary arteries leading to decreased myocardial blood flow or distal platelet emboli with ensuing myocyte necrosis, as described in the third universal definition of myocardial infarction 1.
  • Type 2: Myocardial infarction secondary to an ischemic imbalance, where a condition other than CAD contributes to an imbalance between myocardial oxygen supply and/or demand, such as coronary endothelial dysfunction, coronary artery spasm, coronary embolism, tachy-/brady-arrhythmias, anemia, respiratory failure, hypotension, and hypertension with or without LVH 1.
  • Type 3: Myocardial infarction resulting in death when biomarker values are unavailable, with cardiac death with symptoms suggestive of myocardial ischemia and presumed new ischemic ECG changes or new LBBB, but death occurring before blood samples could be obtained, before cardiac biomarker could rise, or in rare cases cardiac biomarkers were not collected 1.
  • Type 4: Myocardial infarction related to percutaneous coronary intervention (PCI), with subtypes:
    • Type 4a: Myocardial infarction associated with PCI, arbitrarily defined by elevation of cTn values >5 x 99th percentile URL in patients with normal baseline values (<99th percentile URL) or a rise of cTn values >20% if the baseline values are elevated and are stable or falling 1.
    • Type 4b: Myocardial infarction related to stent thrombosis, detected by coronary angiography or autopsy in the setting of myocardial ischemia and with a rise and/or fall of cardiac biomarkers values with at least one value above the 99th percentile URL 1.
  • Type 5: Myocardial infarction related to coronary artery bypass grafting (CABG), arbitrarily defined by elevation of cardiac biomarker values >10 x 99th percentile URL in patients with normal baseline cTn values (<99th percentile URL) 1.

Treatment Approaches

Treatment approaches for NSTEMI typically include antiplatelet therapy, anticoagulation, and other medications such as beta-blockers, statins, and ACE inhibitors, based on individual patient factors and the specific NSTEMI type. The classification of NSTEMI into these types helps guide treatment decisions and improve patient outcomes, as supported by the third universal definition of myocardial infarction 1.

From the Research

Types of Non-ST-Elevation Myocardial Infarction (NSTEMI)

The types of NSTEMI are classified based on the underlying pathophysiology. According to 2, there are five types of myocardial infarction (MI), which can present as NSTEMI:

  • Type 1 MI: characterized by intracoronary atherothrombosis
  • Type 2 MI: caused by myocardial oxygen supply-demand imbalance unrelated to acute coronary atherothrombosis
  • Type 3 MI: identified only after death
  • Type 4 MI: related to percutaneous coronary intervention (PCI)
  • Type 5 MI: related to coronary artery bypass grafting (CABG)

Key Characteristics of Each Type

Some key characteristics of each type of MI are:

  • Type 1 and Type 2 MI are spontaneous events, while Type 4 and Type 5 are procedure-related
  • Most Type 1 and Type 2 MI present as NSTEMI, although both types can also present as ST-elevation MI
  • Patients with Type 2 MI often have multiple comorbidities and causes of in-hospital mortality that are not always cardiovascular-related

Importance of Distinguishing Between Types

It is essential to distinguish between Type 1 and Type 2 NSTEMI early in the clinical course to allow for the use of the most appropriate treatments that will provide the greatest benefit for these patients, as stated in 2. However, the provided studies do not offer detailed information on the specific management and treatment of each type of NSTEMI.

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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