2021 ICD-10-CM Diagnosis Code I21.A1

Myocardial infarction type 2

    2018 - New Code 2019 2020 2021 Billable/Specific Code
  • I21.A1 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2021 edition of ICD-10-CM I21.A1 became effective on October 1, 2020.
  • This is the American ICD-10-CM version of I21.A1 - other international versions of ICD-10 I21.A1 may differ.
Applicable To
  • Myocardial infarction due to demand ischemia
  • Myocardial infarction secondary to ischemic imbalance
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.
  • the underlying cause, such as:
  • anemia (
    ICD-10-CM Diagnosis Code D50.0

    Iron deficiency anemia secondary to blood loss (chronic)

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    Applicable To
    • Posthemorrhagic anemia (chronic)
    Type 1 Excludes
    • acute posthemorrhagic anemia (D62)
    • congenital anemia from fetal blood loss (P61.3)
    D50.0-
    ICD-10-CM Diagnosis Code D64.9

    Anemia, unspecified

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    D64.9
    )
  • chronic obstructive pulmonary disease (
    ICD-10-CM Diagnosis Code J44
    • J44 Other chronic obstructive pulmonary disease
      • J44.0 Chronic obstructive pulmonary disease with (a...
      • J44.1 Chronic obstructive pulmonary disease with (a...
      • J44.9 Chronic obstructive pulmonary disease, unspec...
    J44.-
    )
  • paroxysmal tachycardia (
    ICD-10-CM Diagnosis Code I47.0

    Re-entry ventricular arrhythmia

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    I47.0-
    ICD-10-CM Diagnosis Code I47.9

    Paroxysmal tachycardia, unspecified

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    Applicable To
    • Bouveret (-Hoffman) syndrome
    I47.9
    )
  • shock (
    ICD-10-CM Diagnosis Code R57.0

    Cardiogenic shock

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    Type 2 Excludes
    R57.0-
    ICD-10-CM Diagnosis Code R57.9

    Shock, unspecified

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    Applicable To
    • Failure of peripheral circulation NOS
    R57.9
    )
The following code(s) above I21.A1 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.A1:
  • I00-I99
    2021 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
    2021 ICD-10-CM Range I20-I25

    Ischemic heart diseases

    Use Additional
    • code to identify 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 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.A1 is grouped within Diagnostic Related Group(s) (MS-DRG v38.0):
  • 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.A1 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
Code annotations containing back-references to I21.A1:
  • Type 1 Excludes: I24.8
    , I22
    ICD-10-CM Diagnosis Code I24.8

    Other forms of acute ischemic heart disease

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    Type 1 Excludes
    • myocardial infarction due to demand ischemia (I21.A1)
    ICD-10-CM Diagnosis Code I22

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

      2016 2017 2018 2019 2020 2021 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.A1:
  • 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 Billable/Specific Code
      Applicable To
      • Myocardial infarction (acute) NOS
      • due to
        • demand ischemia I21.A1
        • ischemic imbalance I21.A1
      • secondary to
        • demand ischemia I21.A1
        • ischemic imbalance I21.A1
      • 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 Billable/Specific Code
        Applicable To
        • Subsequent acute myocardial infarction of unspecified site
        • Subsequent myocardial infarction (acute) NOS
        • type 2 I21.A1
      • type 2 I21.A1
  • Ischemia, ischemic I99.8
    ICD-10-CM Diagnosis Code I99.8

    Other disorder of circulatory system

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    • demand (coronary) I24.8
      - see also Angina
      ICD-10-CM Diagnosis Code I24.8

      Other forms of acute ischemic heart disease

        2016 2017 2018 2019 2020 2021 Billable/Specific Code
      Type 1 Excludes
      • myocardial infarction due to demand ischemia (I21.A1)
      • with myocardial infarction I21.A1
      • resulting in myocardial infarction I21.A1

ICD-10-CM Codes Adjacent To I21.A1
I21.1 ST elevation (STEMI) myocardial infarction of inferior wall
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

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