I20.81 ICD-10-CM Code: Angina pectoris with coronary microvascular dysfunction

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for I20.81 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 I20.81 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for I20.81

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

Before you code I20.81

1. I20.81’s title joins a condition with an associated condition or complication. Confirm each component is documented. Where the classification presumes the link through the “with” convention, only a provider statement that the conditions are unrelated defeats it. A combination code is assigned only when it fully identifies the documented conditions; a required second code for the stage, type or manifestation is still reported when the notes ask for it (Guidelines I.B.9, I.A.15).

   Guide: Combination codes →

2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with I20.81. 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 I20.81’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.

   ReviewI25.1, I25.7, I23.7

Consider I20.81. 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 associated condition or complication

Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).

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

• Excludes1 — check before selecting I20.81(3 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with I20.81: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareI25.1, I25.7, I23.7

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

• Use Additional Code — after identifying I20.81(7 notes)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with I20.81 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, 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

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 (4)

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.

• Angina (attack) (cardiac) (chest) (heart) (pectoris) (syndrome) (vasomotor), with, coronary microvascular disease
• Angina (attack) (cardiac) (chest) (heart) (pectoris) (syndrome) (vasomotor), with, coronary microvascular dysfunction
• Disease, diseased, coronary (artery), microvascular, with, angina pectoris
• Dysfunction, coronary microvascular, with, angina pectoris

Don’t confuse I20.81 with…

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

The codes most likely to be picked instead of I20.81 — 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.

• I25.1— 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 with atherosclerotic heart disease of native coronary arteries moves the case to I25.1; the two are not reported together unless documented as unrelated.

  Full comparison: I20.81 vs I25.1 →

• I25.7— 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 atherosclerosis of coronary artery bypass graft(s) and coronary artery of transplanted heart with angina pectoris moves the case to I25.7; the two are not reported together unless documented as unrelated.

  Full comparison: I20.81 vs I25.7 →

• I23.7— 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 postinfarction angina moves the case to I23.7; the two are not reported together unless documented as unrelated.

  Full comparison: I20.81 vs I23.7 →

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. 7 Use Additional Code instructions — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
2. 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
3. 3 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 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

• No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

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 I20.81 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 7 Excludes1 notes: I24 — Other acute ischemic heart diseases (via I20.-), I25.118 — Atherosclerotic heart disease of native coronary artery with other forms of angina pectoris (via I20.8.-), I25.708 — Atherosclerosis of coronary artery bypass graft(s), unspecified, with other forms of angina pectoris (via I20.8.-), I25.718 — Atherosclerosis of autologous vein coronary artery bypass graft(s) with other forms of angina pectoris (via I20.8.-), I25.728 — Atherosclerosis of autologous artery coronary artery bypass graft(s) with other forms of angina pectoris (via I20.8.-), I25.738 — Atherosclerosis of nonautologous biological coronary artery bypass graft(s) with other forms of angina pectoris (via I20.8.-), I25.798 — Atherosclerosis of other coronary artery bypass graft(s) with other forms of angina pectoris (via I20.8.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

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 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, I20.89 — 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, I24.81 — Acute coronary microvascular dysfunction, 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 terms “Dysfunction”, “Angina”; these codes share that main term but sit in a different category of the Tabular List.

G93.89 — Other specified disorders of brain (cerebral), H02.881 — Meibomian gland dysfunction right upper eyelid (meibomian gland, of eyelid, right, upper), 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), I21.B — Myocardial infarction with coronary microvascular dysfunction (coronary microvascular, with, myocardial infarction), I23.7 — Postinfarction angina (post-infarctional), I24.81 — Acute coronary microvascular dysfunction (coronary microvascular, acute), 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), +126 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 I20.81 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 I20.81 with these 7 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 Excludes1 notes

• I24 — Other acute ischemic heart diseases[Excludes1](via I20.-): “angina pectoris (I20.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• I25.118 — Atherosclerotic heart disease of native coronary artery with other forms of angina pectoris[Excludes1](via I20.8.-): “other forms of angina pectoris without atherosclerotic heart disease (I20.8-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• I25.708 — Atherosclerosis of coronary artery bypass graft(s), unspecified, with other forms of angina pectoris[Excludes1](via I20.8.-): “other forms of angina pectoris without atherosclerosis of coronary artery bypass graft (I20.8-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• I25.718 — Atherosclerosis of autologous vein coronary artery bypass graft(s) with other forms of angina pectoris[Excludes1](via I20.8.-): “other forms of angina pectoris without atherosclerosis of autologous vein coronary artery bypass graft(s) (I20.8-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• I25.728 — Atherosclerosis of autologous artery coronary artery bypass graft(s) with other forms of angina pectoris[Excludes1](via I20.8.-): “other forms of angina pectoris without atherosclerosis of autologous artery coronary artery bypass graft(s) (I20.8-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• I25.738 — Atherosclerosis of nonautologous biological coronary artery bypass graft(s) with other forms of angina pectoris[Excludes1](via I20.8.-): “other forms of angina pectoris without atherosclerosis of nonautologous biological coronary artery bypass graft(s) (I20.8-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• I25.798 — Atherosclerosis of other coronary artery bypass graft(s) with other forms of angina pectoris[Excludes1](via I20.8.-): “other forms of angina pectoris without atherosclerosis of other coronary artery bypass graft(s) (I20.8-)”— 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)

MS-DRG Grouper

• 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

• Angina (attack) (cardiac) (chest) (heart) (pectoris) (syndrome) (vasomotor), with, coronary microvascular disease[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Angina (attack) (cardiac) (chest) (heart) (pectoris) (syndrome) (vasomotor), with, coronary microvascular dysfunction[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Disease, diseased, coronary (artery), microvascular, with, angina pectoris[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Dysfunction, coronary microvascular, with, angina pectoris[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

• I20 — Angina pectoris[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I20.0 — Unstable angina[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I20.1 — Angina pectoris with documented spasm[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I20.2 — Refractory angina pectoris[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I20.8 — Other forms of angina pectoris[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I20.89 — Other forms of angina pectoris[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I20.9 — Angina pectoris, 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

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 I20.81 in its code family, with their registry titles.

• I20 — Angina pectoris
• I20.0 — Unstable angina
• I20.1 — Angina pectoris with documented spasm
• I20.2 — Refractory angina pectoris
• I20.8 — Other forms of angina pectoris
• I20.89 — Other forms of angina pectoris
• I20.9 — Angina pectoris, unspecified

View all codes in the I20 family