Coding and coverage · ICD-10-CM

I21 Acute myocardial infarction

Not billable (header)Chapter 9

Report one of the more specific codes below.

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Codes under this one

  • I21.0 ST elevation (STEMI) myocardial infarction of anterior wallHeader
  • I21.1 ST elevation (STEMI) myocardial infarction of inferior wallHeader
  • I21.2 ST elevation (STEMI) myocardial infarction of other sitesHeader
  • 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.A Other type of myocardial infarctionHeader
  • I21.B Myocardial infarction with coronary microvascular dysfunction

Instructional notes

Chapter 9

Excludes2Not included here: the patient may have both; report both when both are present.
  • 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.-)

Section I20-I25

Code also
  • the presence of hypertension (I10-I1A)

This code

Excludes2Not included here: the patient may have both; report both when both are present.
  • old myocardial infarction (I25.2)
  • postmyocardial infarction syndrome (I24.1)
  • subsequent type 1 myocardial infarction (I22.-)
Use additional codeAdd a second code for the full picture.
  • 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)
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

Chapter 9: Diseases of the circulatory system · I20-I25 Ischemic heart diseases (I20-I25)

Source: ICD-10-CM FY 2027 code descriptions and tabular list (CMS and CDC National Center for Health Statistics), effective 2026-10-01 through 2027-09-30 · CMS ICD-10 files. HCC mapping: CMS-HCC V28, payment year 2027. As of 2026-11-04.

Coverage and payment depend on the claim details; confirm with the Medicare Administrative Contractor.