2023

  1. ICD-10-CM Codes
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  2. I00-I99
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  3. I20-I25
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  5. 2023 ICD-10-CM Diagnosis Code I21.A9

2023 ICD-10-CM Diagnosis Code I21.A9

Other myocardial infarction type

    2018 - New Code 2019 2020 2021 2022 2023 Billable/Specific Code
  • I21.A9 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2023 edition of ICD-10-CM I21.A9 became effective on October 1, 2022.
  • This is the American ICD-10-CM version of I21.A9 - other international versions of ICD-10 I21.A9 may differ.
Applicable To
  • Myocardial infarction associated with revascularization procedure
  • Myocardial infarction type 3
  • Myocardial infarction type 4a
  • Myocardial infarction type 4b
  • Myocardial infarction type 4c
  • Myocardial infarction type 5
Code First
Code First Help
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, 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. In most cases the manifestation codes will have in the code title, "in diseases classified elsewhere." Codes with this title are a component of the etiology/manifestation convention. The code title indicates that it is a manifestation code. "In diseases classified elsewhere" codes are never permitted to be used as first listed or principle diagnosis codes. They must be used in conjunction with an underlying condition code and they must be listed following the underlying condition.
  • , if applicable, postprocedural myocardial infarction following cardiac surgery (
    ICD-10-CM Diagnosis Code I97.190

    Other postprocedural cardiac functional disturbances following cardiac surgery

      2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code
    Use Additional
    • code, if applicable, for type 4 or type 5 myocardial infarction, to further specify disorder
    I97.190
    ), or postprocedural myocardial infarction during cardiac surgery (
    ICD-10-CM Diagnosis Code I97.790

    Other intraoperative cardiac functional disturbances during cardiac surgery

      2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code
    I97.790
    )
Code Also
Code Also Help
A code also note instructs that 2 codes may be required to fully describe a condition but the sequencing of the two codes is discretionary, depending on the severity of the conditions and the reason for the encounter.
  • complication, if known and applicable, such as:
  • (acute) stent occlusion (
    ICD-10-CM Diagnosis Code T82.897

    Other specified complication of cardiac prosthetic devices, implants and grafts

      2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code
    T82.897-
    )
  • (acute) stent stenosis (
    ICD-10-CM Diagnosis Code T82.855

    Stenosis of coronary artery stent

      2017 - New Code 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code
    Applicable To
    • In-stent stenosis (restenosis) of coronary artery stent
    • Restenosis of coronary artery stent
    T82.855-
    )
  • (acute) stent thrombosis (
    ICD-10-CM Diagnosis Code T82.867

    Thrombosis due to cardiac prosthetic devices, implants and grafts

      2016 2017 - Revised Code 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code
    T82.867-
    )
  • cardiac arrest due to underlying cardiac condition (
    ICD-10-CM Diagnosis Code I46.2

    Cardiac arrest due to underlying cardiac condition

      2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code
    Code First
    • underlying cardiac condition
    I46.2
    )
  • complication of percutaneous coronary intervention (PCI) (
    ICD-10-CM Diagnosis Code I97.89

    Other postprocedural complications and disorders of the circulatory system, not elsewhere classified

      2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code
    I97.89
    )
  • occlusion of coronary artery bypass graft (
    ICD-10-CM Diagnosis Code T82.218

    Other mechanical complication of coronary artery bypass graft

      2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code
    Applicable To
    • Obstruction, mechanical of coronary artery bypass graft
    • Perforation of coronary artery bypass graft
    • Protrusion of coronary artery bypass graft
    T82.218-
    )
The following code(s) above I21.A9 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to I21.A9:
  • I00-I99
    2023 ICD-10-CM Range I00-I99

    Diseases of the circulatory system

    Type 2 Excludes
    • 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.-)
    Diseases of the circulatory system
  • I20-I25
    2023 ICD-10-CM Range I20-I25

    Ischemic heart diseases

    Code Also
    • the presence of hypertension (I10-I16)
    Ischemic heart diseases
  • I21
    ICD-10-CM Diagnosis Code I21

    Acute myocardial infarction

      2016 2017 2018 - Revised Code 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code
    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
    Type 2 Excludes
    • old myocardial infarction (I25.2)
    • postmyocardial infarction syndrome (I24.1)
    • subsequent type 1 myocardial infarction (I22.-)
    Use Additional
    • 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)
    Acute myocardial infarction
ICD-10-CM I21.A9 is grouped within Diagnostic Related Group(s) (MS-DRG v40.0):
  • 222 Cardiac defibrillator implant with cardiac catheterization with ami, hf or shock with mcc
  • 223 Cardiac defibrillator implant with cardiac catheterization with ami, hf or shock without mcc
  • 280 Acute myocardial infarction, discharged alive with mcc
  • 281 Acute myocardial infarction, discharged alive with cc
  • 282 Acute myocardial infarction, discharged alive without cc/mcc
  • 283 Acute myocardial infarction, expired with mcc
  • 284 Acute myocardial infarction, expired with cc
  • 285 Acute myocardial infarction, expired without cc/mcc

Convert I21.A9 to ICD-9-CM

Code History
  • 2018 (effective 10/1/2017): New code
  • 2019 (effective 10/1/2018): No change
  • 2020 (effective 10/1/2019): No change
  • 2021 (effective 10/1/2020): No change
  • 2022 (effective 10/1/2021): No change
  • 2023 (effective 10/1/2022): No change
Code annotations containing back-references to I21.A9:
  • Type 1 Excludes: I22
    ICD-10-CM Diagnosis Code I22

    Subsequent ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction

      2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code
    Includes
    • acute myocardial infarction occurring within four weeks (28 days) of a previous acute myocardial infarction, regardless of site
    • cardiac infarction
    • coronary (artery) embolism
    • coronary (artery) occlusion
    • coronary (artery) rupture
    • coronary (artery) thrombosis
    • infarction of heart, myocardium, or ventricle
    • recurrent myocardial infarction
    • reinfarction of myocardium
    • rupture of heart, myocardium, or ventricle
    • subsequent type 1 myocardial infarction
    Type 1 Excludes
    • subsequent myocardial infarction, type 2 (I21.A1)
    • subsequent myocardial infarction of other type (type 3) (type 4) (type 5) (I21.A9)
    Use Additional
    • 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)

Diagnosis Index entries containing back-references to I21.A9:
  • Infarct, infarction
    • myocardium, myocardial (acute) (with stated duration of 4 weeks or less) I21.9
      ICD-10-CM Diagnosis Code I21.9

      Acute myocardial infarction, unspecified

        2018 - New Code 2019 2020 2021 2022 2023 Billable/Specific Code
      Applicable To
      • Myocardial infarction (acute) NOS
      • subsequent (recurrent) (reinfarction) I22.9
        ICD-10-CM Diagnosis Code I22.9

        Subsequent ST elevation (STEMI) myocardial infarction of unspecified site

          2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code
        Applicable To
        • Subsequent acute myocardial infarction of unspecified site
        • Subsequent myocardial infarction (acute) NOS
        • type 3 I21.A9
        • type 4 I21.A9
        • type 5 I21.A9
      • associated with revascularization procedure I21.A9
      • type 3 I21.A9
      • type 4 I21.A9 (a) (b) (c)
      • type 5 I21.A9

ICD-10-CM Codes Adjacent To I21.A9
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
I21.2 ST elevation (STEMI) myocardial infarction of other sites
I21.21 ST elevation (STEMI) myocardial infarction involving left circumflex coronary artery
I21.29 ST elevation (STEMI) myocardial infarction involving other sites
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 infarction
I21.A1 Myocardial infarction type 2
I21.A9 Other myocardial infarction type
I22 Subsequent ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction
I22.0 Subsequent ST elevation (STEMI) myocardial infarction of anterior wall
I22.1 Subsequent ST elevation (STEMI) myocardial infarction of inferior wall
I22.2 Subsequent non-ST elevation (NSTEMI) myocardial infarction
I22.8 Subsequent ST elevation (STEMI) myocardial infarction of other sites
I22.9 Subsequent ST elevation (STEMI) myocardial infarction of unspecified site
I23 Certain current complications following ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction (within the 28 day period)
I23.0 Hemopericardium as current complication following acute myocardial infarction
I23.1 Atrial septal defect as current complication following acute myocardial infarction
I23.2 Ventricular septal defect as current complication following acute myocardial infarction

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.

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