I21 ICD-10-CA category: Acute myocardial infarction
I21 isn’t a code on its own. Choose one of the 6 codes beneath it, the one the documentation supports.
Official description
I21Acute myocardial infarction
ICD-10-CA · Canada
Codes in I21
I21 isn’t a code on its own. Open the code that matches what the note documents.
I21.0Acute transmural myocardial infarction of anterior wallI21.1Acute transmural myocardial infarction of inferior wallI21.2Acute transmural myocardial infarction of other sitesI21.3Acute transmural myocardial infarction of unspecified siteI21.4Acute subendocardial myocardial infarctionI21.9Acute myocardial infarction, unspecifiedNotes for I21
As CIHI prints them, with any note I21 takes from the headings above it.
Includes
- Myocardial infarction specified as acute or with a stated duration of 4 weeks (28 days) or less from onset
- With mention of hypertension (I10-I15)From I20-I25 Ischaemic heart diseases
Use additional code
Add a code for this detail when the note documents it.
- Use additional code from category (E10-E14) with fourth and fifth characters .52 to classify any associated diabetes mellitus.
- Use additional code from subcategory (R94.3-) to identify abnormal results of cardiovascular function studies
- Use additional code to identify presence of hypertension.From I20-I25 Ischaemic heart diseases
Excludes
Conditions classified elsewhere.
- Certain current complications following acute myocardial infarction (I23.-)myocardial infarction:• old (I25.2)• specified as chronic or with a stated duration of more than 4 weeks (more than 28 days) from onset (I25.8)• subsequent (I22.-)postmyocardial infarction syndrome (I24.1)
- Certain:• conditions originating in the perinatal period (P00-P96)• infectious and parasitic diseases (A00-B99)complications of pregnancy, childbirth and the puerperium (O00-O99)congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)endocrine, nutritional and metabolic diseases (E00-E90)injury, poisoning and certain other consequences of external causes (S00-T98)neoplasms (C00-D48)symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)systemic connective tissue disorders (M30-M36)transient cerebral ischaemic attacks and related syndromes (G45.-)From Chapter 9: Diseases of the circulatory system (I00-I99)
Note
- For morbidity, duration as used in categories (I21, I22, I24 and I25) refers to the interval elapsing between onset of the ischaemic episode and admission to care.From I20-I25 Ischaemic heart diseases
Where I21 sits
- 1ChapterChapter 9: Diseases of the circulatory system (I00-I99)
- 2Block I20-I25Ischaemic heart diseases
- 3Category I21Acute myocardial infarction
Source and release
- Data release
- ICD-10-CA · FY 2026–2027
- Effective date
- Apr 1, 2026
- Publisher
- CIHI
This page is built from the ICD-10-CA catalog that Vero Codes reads when it suggests codes: Canadian Institute for Health Information’s FY 2026–2027 release, imported from the publisher’s file and checked against it. The description, notes and structured data come from the same record.
Frequently asked questions
Is I21 a valid ICD-10-CA code?
No. I21 (Acute myocardial infarction) is a category heading in CIHI’s ICD-10-CA FY 2026–2027 release. It holds 6 codes; record the one the documentation supports.
Where is I21 in ICD-10-CA?
I21 sits under I20-I25 Ischaemic heart diseases, within Chapter 9: Diseases of the circulatory system (I00-I99).
What coding notes apply to I21?
ICD-10-CA lists Includes, Use additional code, Excludes, Note notes for I21, including those from the headings it sits under. They are listed on this page with where each one comes from.
Which ICD-10-CA release does this page use?
It uses CIHI’s FY 2026–2027 release, in effect from Apr 1, 2026 to Mar 31, 2027. It is a reference: confirm the code against the current list and the payer’s rules before you submit it.