2026 ICD-10-CM Diagnosis Code I21Acute myocardial infarction
I21 is a non-billable ICD-10-CM category code for acute myocardial infarction, so it cannot be submitted on claims. Use a more specific code from this category instead, such as I21.01, I21.02, I21.09, and I21.11.
Code Identity
Code Classification
Specific Coding for Acute myocardial infarctionOverview
Non-specific codes like I21 require more characters. Use one of these billable codes instead:
I21.0 for ST elevation (STEMI) myocardial infarction of anterior wall
Use I21.01 for ST elevation (STEMI) myocardial infarction involving left main coronary artery
Use I21.02 for ST elevation (STEMI) myocardial infarction involving left anterior descending coronary artery
Use I21.09 for ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall
I21.1 for ST elevation (STEMI) myocardial infarction of inferior wall
Use I21.11 for ST elevation (STEMI) myocardial infarction involving right coronary artery
Use I21.19 for ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall
I21.2 for ST elevation (STEMI) myocardial infarction of other sites
Use I21.21 for ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery
Use I21.29 for ST elevation (STEMI) myocardial infarction involving other sites
Use I21.3 for ST elevation (STEMI) myocardial infarction of unspecified site
Use I21.4 for Non-ST elevation (NSTEMI) myocardial infarction
Use I21.9 for Acute myocardial infarction, unspecified
I21.A for Other type of myocardial infarction
Use I21.A1 for Myocardial infarction type 2
Use I21.A9 for Other myocardial infarction type
Use I21.B for Myocardial infarction with coronary microvascular dysfunction
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Includes
- cardiac infarction
- coronary (artery) embolism
- coronary (artery) occlusion
- coronary (artery) rupture
- coronary (artery) thrombosis
- infarction of heart, myocardium, or ventricle
- myocardial infarction specified as acute or with a stated duration of 4 weeks (28 days) or less from onset
Use Additional Code
- code, if applicable, to identify:
- exposure to environmental tobacco smoke Z77.22
- history of tobacco dependence Z87.891
- occupational exposure to environmental tobacco smoke Z57.31
- status post administration of tPA rtPA in a different facility within the last 24 hours prior to admission to current facility Z92.82
- tobacco dependence F17
- tobacco use Z72.0
Type 2 Excludes
- old myocardial infarction I25.2
- postmyocardial infarction syndrome I24.1
- subsequent type 1 myocardial infarction I22
This note appears immediately under a three character code title to further define, or give examples of, the content of the category.
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
Clinical InformationClinical
Acute Myocardial Infarction
necrosis of the myocardium, as a result of interruption of the blood supply to the area. it is characterized by a severe and rapid onset of symptoms that may include chest pain, often radiating to the left arm and left side of the neck, dyspnea, sweating, and palpitations.Acute Myocardial Infarction by ECG Finding|ACUTE MYOCARDIAL INFARCTION|Acute Myocardial Infarction|Acute Myocardial Infarction by EKG Finding
an electrocardiographic finding showing a current of injury with st elevation. no specification is provided for localization. (cdisc)Acute Myocardial Infarction From PCI Complication Type|PCI Acute Angiographic Complication|PCI Acute Angiographic Complication|PCI Acute Angiographic Complication|PCIAAC|PCIAAC
a description of the complications from a percutaneous coronary intervention procedure that lead to an acute myocardial ischemic event.Acute Myocardial Infarction Type|ACMITYPE|ACMITYPE
a classification or description of the acute myocardial infarction.Death due to Acute Myocardial Infarction Related to COVID-19|Death due to acute MI
death by any cardiovascular mechanism (e.g., arrhythmia, sudden death, heart failure (hf), stroke, pulmonary embolus, peripheral arterial disease) less than or equal to 30 days after a myocardial infarction (mi), related to the immediate consequences of the mi, such as progressive hf or recalcitrant arrhythmia in a patient with probable or confirmed acute covid-19.Acute Myocardial Infarction by ECG Finding|ACUTE MYOCARDIAL INFARCTION|Acute Myocardial Infarction|Acute Myocardial Infarction by EKG Finding
an electrocardiographic finding showing a current injury of the myocardium.
Patient EducationClinical
Heart Attack
Each year almost 800,000 Americans have a heart attack. A heart attack happens when blood flow to the heart suddenly becomes blocked. Without the blood coming in, the heart can't get oxygen. If not treated quickly, the heart muscle begins to die.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Code HistoryHistory
Questions About I21Overview
Is I21 (Acute myocardial infarction) a billable code?
No. This is a category header that groups the codes for acute myocardial infarction, and headers cannot be submitted on claims. Claims for acute myocardial infarction need a more specific code from this category, such as I21.01, I21.02, and I21.09.
