ICD-10-CM category I21: Acute myocardial infarction
Category I21 is a heading in chapter 9 (Diseases of the circulatory system (I00-I99)), section Ischemic heart diseases (I20-I25). It is not billable; report one of the 13 complete codes below.
Notes that apply to every I21 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
- Excludes2 (not part of this condition, may be coded together)
- old myocardial infarction (I25.2)
- postmyocardial infarction syndrome (I24.1)
- subsequent type 1 myocardial infarction (I22.-)
- 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)
Billable codes in I21
| Code | Description |
|---|---|
| I21.01 | ST elevation (STEMI) myocardial infarction involving left main coronary artery |
| I21.02 | ST elevation (STEMI) myocardial infarction involving left anterior descending coronary artery |
| I21.09 | ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall |
| I21.11 | ST elevation (STEMI) myocardial infarction involving right coronary artery |
| I21.19 | ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall |
| I21.21 | ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery |
| I21.29 | ST elevation (STEMI) myocardial infarction involving other sites |
| I21.3 | ST elevation (STEMI) myocardial infarction of unspecified site |
| I21.4 | Non-ST elevation (NSTEMI) myocardial infarction |
| I21.9 | Acute myocardial infarction, unspecified |
| I21.A1 | Myocardial infarction type 2 |
| I21.A9 | Other myocardial infarction type |
| I21.B | Myocardial infarction with coronary microvascular dysfunction |
Sources
Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.
- ICD-10-CM FY2027 tabular order file (category titles)Version FY2027 · effective 2026-10-01 · file icd10cm_order_2027.txtSHA-256 38981fb2c1226e2b…
- ICD-10-CM FY2027 tabular list (chapter titles and ranges)Version FY2027 · effective 2026-10-01 · file 2027-code-tables-tabular-index.zipSHA-256 37baa476323714be…
- ICD-10-CM FY2027 code descriptions addenda (codes added, deleted and revised)Version FY2027 · effective 2026-10-01 · file icd10cm_codes_addenda_2027.txtSHA-256 cfba025073235af4…
- ICD-10 MS-DRG Definitions Manual v44 (text)Version v44 · effective 2026-10-01 · file fy2027-fr-icd10-ms-drg-definitions-manual-files-v44.zipSHA-256 ae4f6c11727fe91f…
- IPPS FY2027 Tables 6A-6K: new, invalid and revised ICD-10-CM/PCS codes, CC/MCC list changes and CC exclusionsVersion FY2027 (final rule; not reissued by CN3) · effective 2026-10-01 · file fy2027-ipps-fr-tables-6a-6k.zipSHA-256 ca0af87b0869a405…
- ICD-10-CM FY2027 POA-exempt codes (full list, additions, deletions and revisions)Version FY2027 · effective 2026-10-01 · file 2027-poa-exempt-codes.zipSHA-256 03f55091045024d0…
- ICD-10-CM to CMS-HCC V28 mappings, payment year 2027 initialVersion PY2027 initial ICD-10-CM mappings (dates of service 2026) · effective 2027-01-01 · file 2027 Initial ICD-10-CM Mappings.csvSHA-256 9c260b06d0dd2806…
- Medicare Coverage Database, current Billing and Coding Articles exportVersion MCD release 2026-10-08 · effective 2026-10-04 · file article.csvSHA-256 5e95c4a8ac3664be…
Codes from the FY2027 ICD-10-CM files (all chapters). Report the code that matches the documentation and the Official Guidelines; this list is not coding advice.