I21.0
ST elevation (STEMI) myocardial infarction of anterior wall
I21.0 is a non-billable ICD-10-CM code header for ST elevation (STEMI) myocardial infarction of anterior wall. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are 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 and I21.09 ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wall. Its coding notes include a Use additional code instruction, a Code also instruction and 13 Excludes2 entries.
Guidelines tips
From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.
I21 may continue to be reported while the MI is four weeks old or less. After that, continuing care is coded as aftercare, and a healed MI may be coded I25.2.
A type 1 NSTEMI that evolves to STEMI is coded as STEMI. I21.9 is the default for an unspecified AMI. A nontransmural or subendocardial AMI is still coded as subendocardial when the site is given.
Use additional code
Add the listed code as a secondary code, if known.
- 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)
Code also
Two codes may be needed to describe the condition. This note gives no sequencing order.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (10 notes)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
- systemic connective tissue disorders (M30-M36)
- transient cerebral ischemic attacks and related syndromes (G45.-)
Includes
Further defines or gives examples of the content of the category.
- 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
Inclusion terms
Conditions classified to this code.
- Type 1 ST elevation myocardial infarction of anterior wall
More specific codes under I21.0 3
- I21.01ST elevation (STEMI) myocardial infarction involving left main coronary arteryBillable
- I21.02ST elevation (STEMI) myocardial infarction involving left anterior descending coronary arteryBillable
- I21.09ST elevation (STEMI) myocardial infarction involving other coronary artery of anterior wallBillable