Name: Myocardial infarction type 2
Creator: MedCoder.ai

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives: 9 inclusion terms · 3 Excludes2 · 7 use-additional codes · 5 code-first instructions · 1 code-also instruction
Risk adjustment: CMS-HCC V28: 1 category · CMS-HCC V22 category 86 · RxHCC V08 category 188

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

MS-DRG 280 — ACUTE MYOCARDIAL INFARCTION, DISCHARGED ALIVE WITH MCC (MDC 05)
MS-DRG 281 — ACUTE MYOCARDIAL INFARCTION, DISCHARGED ALIVE WITH CC (MDC 05)
MS-DRG 282 — ACUTE MYOCARDIAL INFARCTION, DISCHARGED ALIVE WITHOUT CC/MCC (MDC 05)
MS-DRG 283 — ACUTE MYOCARDIAL INFARCTION, EXPIRED WITH MCC (MDC 05)
MS-DRG 284 — ACUTE MYOCARDIAL INFARCTION, EXPIRED WITH CC (MDC 05)
MS-DRG 285 — ACUTE MYOCARDIAL INFARCTION, EXPIRED WITHOUT CC/MCC (MDC 05)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

HCC 228 — Acute Myocardial Infarction (supersedes HCC 229)

Other models: CMS-HCC V22 HCC 86 · RxHCC V08 HCC 188

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for I21.A1 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on I21.A1 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

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

Source: inherited from I21

Inclusion Terms

Alternative terms the tabular list files under this code.

Myocardial infarction due to demand ischemia
Myocardial infarction secondary to ischemic imbalance

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

old myocardial infarction (I25.2) Compare I21.A1 vs I25.2 →
postmyocardial infarction syndrome (I24.1) Compare I21.A1 vs I24.1 →
subsequent type 1 myocardial infarction (I22.-) Compare I21.A1 vs I22 →

Source: inherited from I21

Code First

Underlying conditions that must be sequenced before this code.

Code first, if applicable, the underlying cause, such as:
anemia (D50.0-D64.9)
chronic obstructive pulmonary disease (J44.-)
paroxysmal tachycardia (I47.0-I47.9)
I47.0-I47.9: I47.0, I47.1, I47.10, I47.11, I47.19, I47.2, I47.20, I47.21, I47.22, I47.29, I47.9
shock (R57.0-R57.9)
R57.0-R57.9: R57.0, R57.1, R57.8, R57.9

Code Also

Additional codes that may be required to fully describe the encounter.

the presence of hypertension (I10-I1A)

Source: inherited from I20-I25

Use Additional Code

Supplementary codes the tabular list directs you to add.

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)

Source: inherited from I21

Coder workflow for I21.A1

MedCoder structured workflow — derived from this code’s own official record

Choose the right path

Is the underlying (etiologic) condition the Code First note names documented?
Yes → Sequence the underlying condition first, then I21.A1.
No → Continue; do not add an underlying condition the record does not document.
ReviewJ44

Consider I21.A1. Then work the Use Additional Code note and review the Code Also note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement: Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The underlying (etiologic) condition: Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).
The conditions the Use Additional Code note names: Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

Excludes2 — not part of I21.A1(3 notes)
Coding workflow: The conditions named in this note are not included in I21.A1. When the record documents both, both may be reported; the note is a boundary, not a prohibition.
CompareI25.2, I24.1, I22
See the official tabular notes · Guidelines I.A.12.b
Code First — sequencing check(5 notes)
Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before I21.A1. Do not add an underlying condition the record does not document.
ReviewJ44
See the official tabular notes · Guidelines I.A.13
Use Additional Code — after identifying I21.A1(7 notes)
Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with I21.A1 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.
ReviewZ77.22, Z87.891, Z57.31, Z92.82, F17, Z72.0
See the official tabular notes · Guidelines I.A.13
Code Also — related condition(1 note)
Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.
See the official tabular notes · Guidelines I.A.17

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The underlying condition the Code First note names is documented alongside this condition.

Coding question: How are the two sequenced?

Path: Review the Code First note.

Reason: The underlying condition is sequenced first and the manifestation follows (Guidelines I.A.13).

ReviewJ44

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with I21.A1?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

ReviewZ77.22, Z87.891, Z57.31, Z92.82, F17, Z72.0

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Myocardial infarction type 2 is a billable ICD-10-CM diagnosis code (I21.A1).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (8)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.