2027 ICD-10-CM Diagnosis Code I20.81Angina pectoris with coronary microvascular dysfunction

ICD-10-CM Codes›I00–I99›I20-I25›I20

ICD-10-CM I20.81
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

I20.81 is a billable ICD-10-CM diagnosis code for angina pectoris with coronary microvascular dysfunction. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 311. Coders also document this condition as angina pectoris due to microvascular ischemia of myocardium. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Coronary atherosclerosis and other heart disease.

I20.81 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 88 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 88, ESRD (V21) category 88, ESRD (V24) category 88, and RxHCC Part D (V08) category 188 for payment year 2027.

Code Identity

ICD-10-CM Code
I20.81
Billable Status
Yes — Valid for Submission
Code Describes
Angina pectoris with coronary microvascular dysfunction
Short Description
Angina pectoris with coronary microvascular dysfunction
Same as the full description in the CMS dataset.
Parent Code
I20.8
Other forms of angina pectoris

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI20-I25Ischemic heart diseases
CategoryI20Angina pectoris
This CodeI20.81Angina pectoris with coronary microvascular dysfunction

Medicare Risk Adjustment (HCC)Billing

I20.81 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
Dropped in V28 see all codes that no longer risk-adjust
Prior Model (CMS-HCC V24)
HCC 88
V24 retired last contributed to a Medicare Advantage risk score in payment year 2025
Other CMS Models
PACE (CMS-HCC V22): HCC 88 · ESRD (V21): HCC 88 · ESRD (V24): HCC 88
ESRD V21 weights: 0.048 dialysis, 0.129–0.392 functioning graft · ESRD V24 weights: 0.043 dialysis, 0.071–0.280 functioning graft
Part D (RxHCC)
RxHCC 188 — Coronary Artery Disease
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Angina pectoris due to microvascular ischemia of myocardium
  • Cardiac syndrome X
  • Coronary microvascular dysfunction

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to I20.81: its own notes plus those printed at I20.8, I20, block I20-I25, and Chapter 9. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Angina pectoris with coronary microvascular disease

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From I20 Angina pectoris applies to 6 codes
  • angina pectoris with atherosclerotic heart disease of native coronary arteries (I25.1-)
  • atherosclerosis of coronary artery bypass graft(s) and coronary artery of transplanted heart with angina pectoris (I25.7-)
  • postinfarction angina (I23.7)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 9 (I00-I99) Diseases of the circulatory system applies to 1,433 codes
  • 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.-)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From I20.8 Other forms of angina pectoris applies to 2 codes
  • code(s) for symptoms associated with angina equivalent
From I20 Angina pectoris applies to 6 codes
  • code to identify:
  • exposure to environmental tobacco smoke (Z77.22)
  • history of tobacco dependence (Z87.891)
  • occupational exposure to environmental tobacco smoke (Z57.31)
  • tobacco dependence (F17.-)
  • tobacco use (Z72.0)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From Block I20-I25 Ischemic heart diseases applies to 94 codes
  • the presence of hypertension (I10-I1A)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name I20.81, its category, or a range that includes it.

Excludes1 7

These codes carry an Excludes1 note naming I20.81: they are not reported together with it, unless the two conditions are unrelated.

  • I24 Other acute ischemic heart diseases
    angina pectoris (I20.-) names I20.-, which includes this code
  • I25.118 Atherosclerotic heart disease of native coronary artery with other forms of angina pectoris
    other forms of angina pectoris without atherosclerotic heart disease (I20.8-) names I20.8-, which includes this code
  • I25.708 Atherosclerosis of coronary artery bypass graft(s), unspecified, with other forms of angina pectoris
    other forms of angina pectoris without atherosclerosis of coronary artery bypass graft (I20.8-) names I20.8-, which includes this code
  • I25.718 Atherosclerosis of autologous vein coronary artery bypass graft(s) with other forms of angina pectoris
    other forms of angina pectoris without atherosclerosis of autologous vein coronary artery bypass graft(s) (I20.8-) names I20.8-, which includes this code
  • I25.728 Atherosclerosis of autologous artery coronary artery bypass graft(s) with other forms of angina pectoris
    other forms of angina pectoris without atherosclerosis of autologous artery coronary artery bypass graft(s) (I20.8-) names I20.8-, which includes this code
  • I25.738 Atherosclerosis of nonautologous biological coronary artery bypass graft(s) with other forms of angina pectoris
    other forms of angina pectoris without atherosclerosis of nonautologous biological coronary artery bypass graft(s) (I20.8-) names I20.8-, which includes this code
  • I25.798 Atherosclerosis of other coronary artery bypass graft(s) with other forms of angina pectoris
    other forms of angina pectoris without atherosclerosis of other coronary artery bypass graft(s) (I20.8-) names I20.8-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR011
Coronary atherosclerosis and other heart disease
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Angina Pectoris

    the symptom of paroxysmal pain consequent to myocardial ischemia usually of distinctive character, location and radiation. it is thought to be provoked by a transient stressful situation during which the oxygen requirements of the myocardium exceed that supplied by the coronary circulation.

Patient EducationClinical

Angina

Angina is chest pain or discomfort you feel when there is not enough blood flow to your heart muscle. Your heart muscle needs the oxygen that the blood carries. Angina may feel like pressure or a squeezing pain in your chest. It may feel like indigestion. You may also feel pain in your shoulders, arms, neck, jaw, or back.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code History & ChangesHistory

Replacement I20.81 replaces the following previously assigned code(s):

  • I20.8 - Other forms of angina pectoris
FY 2024AddedAdded to the ICD-10-CM code setEffective October 1, 2023.
FY 2025–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About I20.81Overview

What is the ICD-10 code for angina pectoris with coronary microvascular dysfunction?

The ICD-10-CM code for angina pectoris with coronary microvascular dysfunction is I20.81 (sometimes written as I2081). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is I20.81 (Other forms of angina pectoris) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report angina pectoris with coronary microvascular dysfunction on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does I20.81 group to?

When angina pectoris with coronary microvascular dysfunction is the principal diagnosis on an inpatient stay, it groups to MS-DRG 311 (angina Pectoris), which carries a relative weight of 0.6681. Higher weights mean higher Medicare reimbursement.

Can I20.81 be reported with a code from I25.1?

Not as a rule. The Excludes1 note at I20, which applies to I20.81, lists "angina pectoris with atherosclerotic heart disease of native coronary arteries (I25.1-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

Does I20.81 need an additional code?

When the condition applies, yes. The Use Additional Code note at I20.8, which applies to I20.81, reads: code(s) for symptoms associated with angina equivalent. The additional code is reported after I20.81.

Does I20.81 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. I20.81 mapped to HCC 88 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 88 (Angina Pectoris), ESRD (V21) category 88 (Angina Pectoris), ESRD (V24) category 88 (Angina Pectoris), and RxHCC Part D (V08) category 188 (Coronary Artery Disease).