2027 ICD-10-CM Diagnosis Code I24.81Acute coronary microvascular dysfunction

ICD-10-CM Codes›I00–I99›I20-I25›I24

ICD-10-CM I24.81
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

I24.81 is a billable ICD-10-CM diagnosis code for acute 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. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 46 closely related codes. Coders also document this condition as acute microvascular ischemia of myocardium. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Coronary atherosclerosis and other heart disease.

For Medicare Advantage risk adjustment, I24.81 maps to CMS-HCC Category 229 (Unstable Angina and Other Acute Ischemic Heart Disease) under the V28 model, adding a risk factor of about 0.240 for a community, non-dual, aged beneficiary in payment year 2027.

Code Identity

ICD-10-CM Code
I24.81
Billable Status
Yes — Valid for Submission
Code Describes
Acute coronary microvascular dysfunction
Short Description
Acute coronary microvascular dysfunction
Same as the full description in the CMS dataset.
Parent Code
I24.8
Other forms of acute ischemic heart disease

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI20-I25Ischemic heart diseases
CategoryI24Other acute ischemic heart diseases
This CodeI24.81Acute coronary microvascular dysfunction

Medicare Risk Adjustment (HCC)Billing

I24.81 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.

CMS-HCC V28 Category (Payment Model)
HCC 229— Unstable Angina and Other Acute Ischemic Heart Disease
Payment HCC · PY 2027 one of 25 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.240
community, non-dual, aged · ranges 0.240–0.458 across segments
Hierarchy
Superseded by HCC 228
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 87
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 87 · ESRD (V21): HCC 87 · ESRD (V24): HCC 87
ESRD V21 weights: 0.116 dialysis, 0.258–0.392 functioning graft · ESRD V24 weights: 0.120 dialysis, 0.209–0.463 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.

  • Acute microvascular ischemia of myocardium
  • Acute myocardial ischemia
  • Coronary microvascular dysfunction

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to I24.81: its own notes plus those printed at I24.8, I24, 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.

  • Acute (presentation of) coronary microvascular disease

Excludes1

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

From I24.8 Other forms of acute ischemic heart disease applies to 2 codes
  • myocardial infarction due to demand ischemia (I21.A1)
From I24 Other acute ischemic heart diseases applies to 5 codes
  • angina pectoris (I20.-)
  • transient myocardial ischemia in newborn (P29.4)

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 I24 Other acute ischemic heart diseases applies to 5 codes
  • non-ischemic myocardial injury (I5A)
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.-)

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 I24.81, its category, or a range that includes it.

Excludes2 3

These codes carry an Excludes2 note naming I24.81: its condition is not part of those codes, and both may be reported when the patient has both.

  • I5A Non-ischemic myocardial injury (non-traumatic)
    other acute ischemic heart diseases (I24.-) names I24.-, which includes this code
  • I74 Arterial embolism and thrombosis
    coronary embolism and thrombosis (I21-I25) names I21-I25, which includes this code
  • I82 Other venous embolism and thrombosis
    coronary (I21-I25) names I21-I25, 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

Patient EducationClinical

Heart Diseases

Heart disease is a general term that includes many types of heart problems. It's a type of cardiovascular disease, which means heart and blood vessel disease.

The full article covers:

  • What is heart disease?
  • What are the types of heart disease?
  • What causes heart diseases?
  • Who is more likely to develop heart diseases?
  • What are the symptoms of heart disease?
  • How are heart diseases diagnosed?
  • What are the treatments for heart disease?
  • Can heart diseases be prevented?

Read the full article at MedlinePlus

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

Code History & ChangesHistory

Replacement I24.81 replaces the following previously assigned code(s):

  • I24.8 - Other forms of acute ischemic heart disease
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 I24.81Overview

What is the ICD-10 code for acute coronary microvascular dysfunction?

The ICD-10-CM code for acute coronary microvascular dysfunction is I24.81 (sometimes written as I2481). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is I24.81 (Other forms of acute ischemic heart disease) a billable code?

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

What MS-DRG does I24.81 group to?

When acute 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.

Is I24.81 a CC or MCC?

CMS lists I24.81 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 46 closely related codes in its exclusion list.

Can I24.81 be reported with I21.A1?

Not as a rule. The Excludes1 note at I24.8, which applies to I24.81, lists "myocardial infarction due to demand ischemia (I21.A1)". 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).

What HCC is I24.81?

I24.81 (acute coronary microvascular dysfunction) maps to CMS-HCC Category 229 (Unstable Angina and Other Acute Ischemic Heart Disease), commonly written as HCC 229, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 87 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 188.

Does I24.81 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, I24.81 adds a risk adjustment factor of about 0.240 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.240 to 0.458 depending on the payment segment). A more severe related category (HCC 228) supersedes it when both are reported. See the full factor table on the HCC 229 category page.