I24.81 ICD-10-CM Code: Acute coronary microvascular dysfunction

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for I24.81 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 I24.81 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for I24.81

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

Before you code I24.81

1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with I24.81. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support a condition named in I24.81’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewI21.A1, I20, P29.4

Consider I24.81. Then 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).

Acuity

Acute or chronic as documented; when both are documented and separate codes exist, both are reported with the acute code first (Guidelines I.B.8).

Official instructions as workflow

• Excludes1 — check before selecting I24.81(3 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with I24.81: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareI21.A1, I20, P29.4

  See the official tabular notes · Guidelines I.A.12.a

• Excludes2 — not part of I24.81(1 note)

  Coding workflow: The conditions named in this note are not included in I24.81. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareI5A

  See the official tabular notes · Guidelines I.A.12.b

• 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

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.

Indexed Clinical Terms (2)

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.

• Disease, diseased, coronary (artery), microvascular, acute
• Dysfunction, coronary microvascular, acute

Don’t confuse I24.81 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of I24.81 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• I21.A1— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of myocardial infarction due to demand ischemia moves the case to I21.A1; the two are not reported together unless documented as unrelated.

  Full comparison: I24.81 vs I21.A1 →

• I20— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of angina pectoris moves the case to I20; the two are not reported together unless documented as unrelated.

  Full comparison: I24.81 vs I20 →

• P29.4— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of transient myocardial ischemia in newborn moves the case to P29.4; the two are not reported together unless documented as unrelated.

  Full comparison: I24.81 vs P29.4 →

• I5A— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of non-ischemic myocardial injury adds I5A; it is not part of this code and both may be reported when both are documented.

  Full comparison: I24.81 vs I5A →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

1. 1 Code Also note — a second code may apply; the guidelines leave its sequencing to the circumstances of the encounter. See the Code Also notes
2. 3 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
3. 1 Excludes2 entry — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name I24.81 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 3 Excludes2 notes: I5A — Non-ischemic myocardial injury (non-traumatic) (via I24.-), I74 — Arterial embolism and thrombosis (via I24.-), I82 — Other venous embolism and thrombosis (via I24.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 46 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 1 MS-DRG: DRG 311 (MDC 05).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):CIR011 — Coronary atherosclerosis and other heart disease (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

I21.9 — Acute myocardial infarction, unspecified, I21.A1 — Myocardial infarction type 2, I21.A9 — Other myocardial infarction type, 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, I24.0 — Acute coronary thrombosis not resulting in myocardial infarction, I24.1 — Dressler's syndrome, I24.89 — Other forms of acute ischemic heart disease, I24.9 — Acute ischemic heart disease, unspecified, I25.5 — Ischemic cardiomyopathy, I25.6 — Silent myocardial ischemia, I25.702 — Atherosclerosis of coronary artery bypass graft(s), unspecified, with refractory angina pectoris, I25.712 — Atherosclerosis of autologous vein coronary artery bypass graft(s) with refractory angina pectoris, I25.722 — Atherosclerosis of autologous artery coronary artery bypass graft(s) with refractory angina pectoris, I25.732 — Atherosclerosis of nonautologous biological coronary artery bypass graft(s) with refractory angina pectoris, I25.752 — Atherosclerosis of native coronary artery of transplanted heart with refractory angina pectoris, I25.762 — Atherosclerosis of bypass graft of coronary artery of transplanted heart with refractory angina pectoris, +25 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Unstable Angina and Other Acute Ischemic Heart Disease) for risk-adjusted payment.

I23.1 — Atrial septal defect as current complication following acute myocardial infarction, I23.2 — Ventricular septal defect as current complication following acute myocardial infarction, I23.3 — Rupture of cardiac wall without hemopericardium as current complication following acute myocardial infarction, I23.4 — Rupture of chordae tendineae as current complication following acute myocardial infarction, I23.5 — Rupture of papillary muscle as current complication following acute myocardial infarction, I23.6 — Thrombosis of atrium, auricular appendage, and ventricle as current complications following acute myocardial infarction, I23.7 — Postinfarction angina, I23.8 — Other current complications following acute myocardial infarction, I24.0 — Acute coronary thrombosis not resulting in myocardial infarction, I24.1 — Dressler's syndrome, I24.89 — Other forms of acute ischemic heart disease, I24.9 — Acute ischemic heart disease, unspecified, I25.110 — Atherosclerotic heart disease of native coronary artery with unstable angina pectoris, I25.700 — Atherosclerosis of coronary artery bypass graft(s), unspecified, with unstable angina pectoris, I25.710 — Atherosclerosis of autologous vein coronary artery bypass graft(s) with unstable angina pectoris, I25.720 — Atherosclerosis of autologous artery coronary artery bypass graft(s) with unstable angina pectoris, I25.730 — Atherosclerosis of nonautologous biological coronary artery bypass graft(s) with unstable angina pectoris, I25.750 — Atherosclerosis of native coronary artery of transplanted heart with unstable angina, I25.760 — Atherosclerosis of bypass graft of coronary artery of transplanted heart with unstable angina, I25.790 — Atherosclerosis of other coronary artery bypass graft(s) with unstable angina pectoris, +4 more

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Acute Myocardial Infarction

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Coronary atherosclerosis and other heart disease).

I20.0 — Unstable angina, I20.1 — Angina pectoris with documented spasm, I20.2 — Refractory angina pectoris, I20.8 — Other forms of angina pectoris, I20.81 — Angina pectoris with coronary microvascular dysfunction, I20.89 — Other forms of angina pectoris, I20.9 — Angina pectoris, unspecified, I24.0 — Acute coronary thrombosis not resulting in myocardial infarction, I24.8 — Other forms of acute ischemic heart disease, I24.89 — Other forms of acute ischemic heart disease, I24.9 — Acute ischemic heart disease, unspecified, I25.10 — Atherosclerotic heart disease of native coronary artery without angina pectoris, I25.110 — Atherosclerotic heart disease of native coronary artery with unstable angina pectoris, I25.111 — Atherosclerotic heart disease of native coronary artery with angina pectoris with documented spasm, I25.112 — Atherosclerotic heart disease of native coronary artery with refractory angina pectoris, I25.118 — Atherosclerotic heart disease of native coronary artery with other forms of angina pectoris, I25.119 — Atherosclerotic heart disease of native coronary artery with unspecified angina pectoris, I25.2 — Old myocardial infarction, I25.5 — Ischemic cardiomyopathy, I25.6 — Silent myocardial ischemia, +47 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Dysfunction”; these codes share that main term but sit in a different category of the Tabular List.

H02.882 — Meibomian gland dysfunction right lower eyelid (meibomian gland, of eyelid, right, lower), H02.883 — Meibomian gland dysfunction of right eye, unspecified eyelid (meibomian gland, of eyelid, right), H02.884 — Meibomian gland dysfunction left upper eyelid (meibomian gland, of eyelid, left, upper), H02.885 — Meibomian gland dysfunction left lower eyelid (meibomian gland, of eyelid, left, lower), H02.886 — Meibomian gland dysfunction of left eye, unspecified eyelid (meibomian gland, of eyelid, left), H02.889 — Meibomian gland dysfunction of unspecified eye, unspecified eyelid (meibomian gland, of eyelid), H02.88A — Meibomian gland dysfunction right eye, upper and lower eyelids (meibomian gland, of eyelid, right, upper and lower eyelids), H02.88B — Meibomian gland dysfunction left eye, upper and lower eyelids (meibomian gland, of eyelid, left, upper and lower eyelids), I20.81 — Angina pectoris with coronary microvascular dysfunction (coronary microvascular, with, angina pectoris), I21.B — Myocardial infarction with coronary microvascular dysfunction (coronary microvascular, with, myocardial infarction), I25.85 — Chronic coronary microvascular dysfunction (coronary microvascular), I27.841 — Fontan-associated lymphatic dysfunction (lymphatic, Fontan-associated), I49.5 — Sick sinus syndrome (sinoatrial node), I50.9 — Heart failure, unspecified (ventricular, with congestive heart failure), I51.81 — Takotsubo syndrome (left ventricular, following sudden emotional stress), I51.89 — Other ill-defined heart diseases (heart), I51.9 — Heart disease, unspecified (ventricular), J4A.0 — Restrictive allograft syndrome (chronic, lung allograft, mixed), J4A.8 — Other chronic lung allograft dysfunction (chronic, lung allograft, specified NEC), J4A.9 — Chronic lung allograft dysfunction, unspecified (chronic, lung allograft), +115 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Lipid Panel, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of I24.81 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run I24.81 with these 3 related codes in Claim Check

Hierarchy

• I00-I99 — Chapter 9: Diseases of the Circulatory System (I00-I99) (I00-I99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I20-I25 — Ischemic heart diseases[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes2 notes

• I5A — Non-ischemic myocardial injury (non-traumatic)[Excludes2](via I24.-): “other acute ischemic heart diseases (I24.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• I74 — Arterial embolism and thrombosis[Excludes2](via I24.-): “coronary embolism and thrombosis (I21-I25)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• I82 — Other venous embolism and thrombosis[Excludes2](via I24.-): “coronary (I21-I25)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• CIR011 — Coronary atherosclerosis and other heart disease[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

Risk adjustment (CMS-HCC)

• HCC 229 — Unstable Angina and Other Acute Ischemic Heart Disease [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 311 — ANGINA PECTORIS[MS-DRG]: “ANGINA PECTORIS (MDC 05)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 05 — Diseases and Disorders of the Circulatory System[MDC crossing]: “Diseases and Disorders of the Circulatory System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 17,209 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Disease, diseased, coronary (artery), microvascular, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Dysfunction, coronary microvascular, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

• I24 — Other acute ischemic heart diseases[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I24.0 — Acute coronary thrombosis not resulting in myocardial infarction[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I24.1 — Dressler's syndrome[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I24.8 — Other forms of acute ischemic heart disease[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I24.89 — Other forms of acute ischemic heart disease[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I24.9 — Acute ischemic heart disease, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Change history

• FY2024 — Added to the code set[Change history]— CMS release files (code change ledger) · icd10cm-fy2024

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Risk adjustment Official source data

2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to I24.81 in its code family, with their registry titles.

• I24 — Other acute ischemic heart diseases
• I24.0 — Acute coronary thrombosis not resulting in myocardial infarction
• I24.1 — Dressler's syndrome
• I24.8 — Other forms of acute ischemic heart disease
• I24.89 — Other forms of acute ischemic heart disease
• I24.9 — Acute ischemic heart disease, unspecified

View all codes in the I24 family