I21.A
Other type of myocardial infarction
I21.A is a non-billable ICD-10-CM code header for other type of myocardial infarction. 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.A1 Myocardial infarction type 2 and I21.A9 Other myocardial infarction type. Its coding notes include a Use additional code instruction, a Code also instruction and 13 Excludes2 entries.
Guidelines tip
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.
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