ICD-10 · PDGM grouping
I21 Acute myocardial infarction
All 13 codes in the I21 family, with the PDGM clinical group, comorbidity subgroup and primary-position rule CMS assigns, read from the CMS grouper crosswalk v07.2.26 and the CDC FY2027 code file.
Codes in family
13
Can lead a claim
13
Cannot lead a claim
0
What CMS assigns to I21
All 13 codes group to MMTA - Cardiac and Circulatory. None of the 13 is assigned a comorbidity subgroup. Every code can lead a claim. CMS attaches a code-first note to 2 of the 13.
Code first
CMS grouper convention 61, on I21.A1. Code first:
- , if applicable, the underlying cause, such as:
- anemia (D50.0-D64.9)
- chronic obstructive pulmonary disease (J44.-)
- paroxysmal tachycardia (I47.0-I47.9)
- shock (R57.0-R57.9)
CMS grouper convention 62, on I21.A9. Code first:
- , if applicable, postprocedural myocardial infarction following cardiac surgery (I97.190), or postprocedural myocardial infarction during cardiac surgery (I97.790)
Every code in I21
Descriptions are CDC’s FY2027 wording; where CMS’s grouper abbreviates one, its form is shown beneath.
| Code | Description | Primary position | Clinical group | Comorbidity subgroup |
|---|---|---|---|---|
| I21.0 ST elevation (STEMI) myocardial infarction of anterior wall | ||||
| I21.01 | ST elevation (STEMI) myocardial infarction involving left main coronary arteryCMS: STEMI involving left main coronary artery | Can lead a claim | H | None |
| I21.02 | ST elevation (STEMI) myocardial infarction involving left anterior descending coronary arteryCMS: STEMI involving left anterior descending coronary artery | Can lead a claim | H | None |
| I21.09 | ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wallCMS: STEMI involving oth coronary artery of anterior wall | Can lead a claim | H | None |
| I21.1 ST elevation (STEMI) myocardial infarction of inferior wall | ||||
| I21.11 | ST elevation (STEMI) myocardial infarction involving right coronary arteryCMS: STEMI involving right coronary artery | Can lead a claim | H | None |
| I21.19 | ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wallCMS: STEMI involving oth coronary artery of inferior wall | Can lead a claim | H | None |
| I21.2 ST elevation (STEMI) myocardial infarction of other sites | ||||
| I21.21 | ST elevation (STEMI) myocardial infarction involving left circumflex coronary arteryCMS: STEMI involving left circumflex coronary artery | Can lead a claim | H | None |
| I21.29 | ST elevation (STEMI) myocardial infarction involving other sitesCMS: STEMI involving oth sites | Can lead a claim | H | None |
| I21.3 | ST elevation (STEMI) myocardial infarction of unspecified siteCMS: ST elevation (STEMI) myocardial infarction of unsp site | Can lead a claim | H | None |
| I21.4 | Non-ST elevation (NSTEMI) myocardial infarction | Can lead a claim | H | None |
| I21.9 | Acute myocardial infarction, unspecified | Can lead a claim | H | None |
| I21.A Other type of myocardial infarction | ||||
| I21.A1 | Myocardial infarction type 2 | Can lead a claim, code first applies | H | None |
| I21.A9 | Other myocardial infarction type | Can lead a claim, code first applies | H | None |
| I21.B | Myocardial infarction with coronary microvascular dysfunctionCMS: Myocardial infarction with coronary microvascular dysfnct | Can lead a claim | H | None |
Sources: CMS HH PPS Grouper Software v07.2.26, effective 2026-10-01, for the clinical group, comorbidity subgroup, code-first conventions and primary-position flags; CDC NCHS ICD-10-CM FY2027 code descriptions for the family title and code wording. This is the crosswalk Medicare runs a claim through. Grouping also depends on admission source, timing, the OASIS functional items and the rest of the diagnosis list.
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