2022 ICD-10-CM Code I21.A9

Other myocardial infarction type

Version 2021
Replaced Code

Valid for Submission

ICD-10:I21.A9
Short Description:Other myocardial infarction type
Long Description:Other myocardial infarction type

Code Classification

  • Diseases of the circulatory system (I00–I99)
    • Ischemic heart diseases (I20-I25)
      • Acute myocardial infarction (I21)

I21.A9 is a billable diagnosis code used to specify a medical diagnosis of other myocardial infarction type. The code I21.A9 is valid during the fiscal year 2022 from October 01, 2021 through September 30, 2022 for the submission of HIPAA-covered transactions.

Replaced Code

This code was replaced in the 2022 ICD-10 code set with the code(s) listed below. The National Center for Health Statistics (NCHS) has published an update to the ICD-10-CM diagnosis codes which became effective October 1, 2021. This code was replaced for the FY 2022 (October 1, 2021 - September 30, 2022).


  • I5A - Non-ischemic myocardial injury (non-traumatic)

Tabular List of Diseases and Injuries

The Tabular List of Diseases and Injuries is a list of ICD-10 codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more. The following references are applicable to the code I21.A9:


Inclusion Terms

Inclusion Terms
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.

Code First

Code First
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.

Code Also

Code Also
A "code also" note instructs that two codes may be required to fully describe a condition, but this note does not provide sequencing direction.

Index to Diseases and Injuries

The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10 code(s). The following references for the code I21.A9 are found in the index:

Replacement Code

I21A9 replaces the following previously assigned ICD-10 code(s):

Convert I21.A9 to ICD-9 Code

The General Equivalency Mapping (GEM) crosswalk indicates an approximate mapping between the ICD-10 code I21.A9 its ICD-9 equivalent. The approximate mapping means there is not an exact match between the ICD-10 code and the ICD-9 code and the mapped code is not a precise representation of the original code.

Code History

  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018