I21: Acute myocardial infarction
Codes under I21 (Acute myocardial infarction). A ✓ marks a billable (fully specified) code; category codes without a ✓ are not billable on their own.
| Code | Description | Billable |
|---|---|---|
| I21.0 | ST elevation (STEMI) myocardial infarction of anterior wall | — |
| I21.0 | ST elevation (STEMI) myocardial infarction of anterior wall | — |
| I21.01 | ST elevation (STEMI) myocardial infarction involving left main coronary artery | ✓ |
| I21.01 | ST elevation (STEMI) myocardial infarction involving left main coronary artery | ✓ |
| I21.1 | ST elevation (STEMI) myocardial infarction of inferior wall | — |
| I21.1 | ST elevation (STEMI) myocardial infarction of inferior wall | — |
| I21.02 | ST elevation (STEMI) myocardial infarction involving left anterior descending coronary artery | ✓ |
| I21.02 | ST elevation (STEMI) myocardial infarction involving left anterior descending coronary artery | ✓ |
| I21.2 | ST elevation (STEMI) myocardial infarction of other sites | — |
| I21.2 | ST elevation (STEMI) myocardial infarction of other sites | — |
| I21.3 | ST elevation (STEMI) myocardial infarction of unspecified site | ✓ |
| I21.3 | ST elevation (STEMI) myocardial infarction of unspecified site | ✓ |
| I21.4 | Non-ST elevation (NSTEMI) myocardial infarction | ✓ |
| I21.4 | Non-ST elevation (NSTEMI) myocardial infarction | ✓ |
| I21.09 | ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall | ✓ |
| I21.09 | ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall | ✓ |
| I21.9 | Acute myocardial infarction, unspecified | ✓ |
| I21.9 | Acute myocardial infarction, unspecified | ✓ |
| I21.11 | ST elevation (STEMI) myocardial infarction involving right coronary artery | ✓ |
| 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 | ✓ |
| I21.19 | ST elevation (STEMI) myocardial infarction involving other coronary artery of inferior wall | ✓ |
| I21.21 | ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery | ✓ |
| I21.21 | ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery | ✓ |
| I21.29 | ST elevation (STEMI) myocardial infarction involving other sites | ✓ |
| I21.29 | ST elevation (STEMI) myocardial infarction involving other sites | ✓ |
| I21.A | Other type of myocardial infarction | — |
| I21.A | Other type of myocardial infarction | — |
| I21.A1 | Myocardial infarction type 2 | ✓ |
| I21.A1 | Myocardial infarction type 2 | ✓ |
| I21.A9 | Other myocardial infarction type | ✓ |
| I21.A9 | Other myocardial infarction type | ✓ |
| I21.B | Myocardial infarction with coronary microvascular dysfunction | ✓ |
| I21.B | Myocardial infarction with coronary microvascular dysfunction | ✓ |
Frequently asked questions
What is ICD-10-CM code I21?
I21 is an ICD-10-CM category covering Acute myocardial infarction. It contains 34 more specific diagnosis codes, 26 of which are billable.
Is I21 a billable code?
No — I21 is a category header and isn't billable on its own. Code to the highest level of specificity using one of its subcodes (for example I21.0 — ST elevation (STEMI) myocardial infarction of anterior wall). 26 of the 34 codes under I21 are billable.
What codes fall under I21?
I21 includes I21.0, I21.0, I21.01, I21.01, I21.1, plus 29 more. See the full list with descriptions and billable status above.
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Informational only, not coding or medical advice. Verify against the official ICD-10-CM (FY2026) and your payer's guidelines.
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