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I21.A9 vs I97.190

I21.A9 (Other myocardial infarction type) compared with I97.190 (Other postprocedural cardiac functional disturbances following cardiac surgery), from the official CMS tabular data.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Summary

These codes can be reported together, with I97.190 sequenced before I21.A9 as the tabular note instructs.

Official rule
What is different?

The conditions named.I21.A9 is “Other myocardial infarction type”; I97.190 is “Other postprocedural cardiac functional disturbances following cardiac surgery”.

Registry fact

Can these codes be reported together?

Yes, in the order the notes give.I97.190 is listed before I21.A9; the sequencing answer below quotes the instruction.

Official ruleGuide: Code First vs Use Additional Code vs Code Also

Are there sequencing instructions?

Yes.Sequence I97.190 before I21.A9: I21.A9 carries a Code First instruction covering I97.190 (“, if applicable, postprocedural myocardial infarction following cardiac surgery (I97.190), or postprocedural myocardial infarction during cardiac surgery (I97.790)”).

Official ruleGuide: Code First vs Use Additional Code vs Code Also

Nothing found in 4 other checks; 1 check does not apply
Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code.

Official rule

Is there an Excludes2 relationship?

None.Neither entry carries an Excludes2 note that names the other code. I21.A9 carries 3 Excludes2 notes and I97.190 carries 3 Excludes2 notes covering other codes; the side-by-side table quotes them.

Official rule

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

No.Both are billable codes, and neither contains the other.

Registry fact

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Yes — in the order the notes give.

No Excludes1/Excludes2 relationship exists between these codes in the official tabular list. The sequencing instruction below sets which code is listed first on the claim.

Sequencing on the claim

Sequencing

Sequencing relationship

1st
I97.190
Other postprocedural cardiac functional disturbances following cardiac surgery
→
then
I21.A9
Other myocardial infarction type

What we found

Sequence I97.190 before I21.A9

I21.A9 carries a Code First instruction covering I97.190: “, if applicable, postprocedural myocardial infarction following cardiac surgery (I97.190), or postprocedural myocardial infarction during cardiac surgery (I97.790)”

What to review

On a claim that carries both, list I97.190 ahead of I21.A9; the manifestation is never the principal diagnosis.

Guide: Code First vs Use Additional Code vs Code Also

Why it matters

A "Code first" note means the underlying etiology is sequenced ahead of this manifestation code on the claim.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.B.7 — Multiple coding for a single condition · applies to: Code first / Use additional code

    In addition to the etiology/manifestation convention that requires two codes to fully describe a single condition that affects multiple body systems, there are other single conditions that also require more than one code. “Use additional code” notes are found in the Tabular List at codes that are not part of an etiology/manifestation pair where a secondary code is useful to fully describe a condition. The sequencing rule is the same as the etiology/manifestation pair, “use additional code” indicates that a secondary code should be added, if known. For example, for bacterial infections that are not included in chapter 1, a secondary code from category B95, Streptococcus, Staphylococcus, and Enterococcus, as the cause of diseases classified elsewhere, or B96, Other bacterial agents as the cause of diseases classified elsewhere, may be required to identify the bacterial organism causing the infection. A “use additional code” note will normally be found at the infectious disease code, indicating a need for the organism code to be added as a secondary code. “Code first” notes are also under certain codes that are not specifically manifestation codes but may be due to an underlying cause. When there is a “code first” note and an underlying condition is present, the underlying condition should be sequenced first, if known. […]

    ICD-10-CM Official Guidelines FY2027

  • Section I.A.13 — Etiology/manifestation convention (“code first”, “use additional code” and “in diseases classified elsewhere” notes) · applies to: Etiology/manifestation convention

    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, if applicable, 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 principal diagnosis codes. They must be used in conjunction with an underlying condition code and they must be listed following the underlying condition. See category F02, Dementia in other diseases classified elsewhere, for an example of this convention. There are manifestation codes that do not have “in diseases classified elsewhere” in the title. For such codes, there is a “use additional code” note at the etiology code and a “code first” note at the manifestation code, and the rules for sequencing apply. […]

    ICD-10-CM Official Guidelines FY2027

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

Similar descriptions do not make codes interchangeable. The documentation and the official instructions decide which code applies.

Official descriptionDiffers
I21.A9

Other myocardial infarction type

I97.190

Other postprocedural cardiac functional disturbances following cardiac surgery

StatusSame for both
Billable
Excludes2Differs
I21.A9
  • old myocardial infarction (I25.2)
  • postmyocardial infarction syndrome (I24.1)
  • subsequent type 1 myocardial infarction (I22.-)
I97.190
  • acute pulmonary insufficiency following thoracic surgery (J95.1)
  • intraoperative cardiac functional disturbances (I97.7-)
  • postprocedural shock (T81.1-)
Code firstDiffers
I21.A9
  • , if applicable, postprocedural myocardial infarction following cardiac surgery (I97.190), or postprocedural myocardial infarction during cardiac surgery (I97.790)
I97.190

None at this code

Use additional codeDiffers
I21.A9
  • 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)
I97.190
  • code, if applicable, for type 4 or type 5 myocardial infarction, to further specify disorder
  • code, if applicable, to further specify disorder
Code alsoDiffers
I21.A9
  • complication, if known and applicable, such as:
  • (acute) stent occlusion (T82.897-)
  • (acute) stent stenosis (T82.855-)
  • (acute) stent thrombosis (T82.867-)
  • cardiac arrest due to underlying cardiac condition (I46.2)
  • complication of percutaneous coronary intervention (PCI) (I97.89)
  • occlusion of coronary artery bypass graft (T82.218-)
  • the presence of hypertension (I10-I1A)
I97.190

None at this code

CategoryDiffers
I21.A9

I21 Acute myocardial infarction

I97.190

I97 Intraoperative and postprocedural complications and disorders of circulatory system, not elsewhere classified

ChapterSame for both

I00-I99 — Diseases of the Circulatory System (I00-I99)

IncludesDiffers
I21.A9
  • 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
  • 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
I97.190

None at this code

No Excludes1 and 7th character note at either code.

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on. In a row that differs, each code’s own notes are listed under it, and the notes every code shares are listed once beneath them.

Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources