2027 ICD-10-CM Diagnosis Code I25.9Chronic ischemic heart disease, unspecified

ICD-10-CM Codes›I00–I99›I20-I25›I25

ICD-10-CM I25.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

I25.9 is a billable ICD-10-CM diagnosis code for chronic ischemic heart disease, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 302 through 303. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Coronary atherosclerosis and other heart disease.

I25.9 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 188 for payment year 2027.

This medical diagnosis code is frequently used in Cardiology medical specialties to designate conditions such selected atherosclerosis, ischemia, and infarction.

Code Identity

ICD-10-CM Code
I25.9
Billable Status
Yes — Valid for Submission
Code Describes
Chronic ischemic heart disease, unspecified
Short Description
Chronic ischemic heart disease, unspecified
Same as the full description in the CMS dataset.
Parent Code
I25
Chronic ischemic heart disease

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI20-I25Ischemic heart diseases
CategoryI25Chronic ischemic heart disease
This CodeI25.9Chronic ischemic heart disease, unspecified

Medicare Risk Adjustment (HCC)Billing

I25.9 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
no payment category in the model that pays 100% of MA risk scores
Prior Model (CMS-HCC V24)
Not mapped under V24
this diagnosis newly risk-adjusts under the V28 model
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.

  • Anterior myocardial ischemia
  • Anteroapical myocardial ischemia
  • Anterolateral myocardial ischemia
  • Anteroseptal myocardial ischemia
  • Apical myocardial ischemia
  • Chronic ischemic heart disease
  • Chronic myocardial ischemia
  • Decreased myocardial ischemia compared to prior study
  • EKG myocardial ischemia
  • EKG: inferior ischemia
  • Hibernating myocardium
  • Increased myocardial ischemia compared to prior study
  • Inferior myocardial ischemia
  • Inferolateral myocardial ischemia
  • Inferolateral myocardial ischemia with posterior extension
  • Ischemic heart disease
  • Ischemic myocardial dysfunction
  • Lateral myocardial ischemia
  • Mixed myocardial ischemia and infarction
  • Myocardial ischemia
  • Myocardial ischemia manifest on stress test status post myocardial infarction
  • Myocardial ischemia of ventricular septum
  • New myocardial ischemia compared to prior study
  • Posterior myocardial ischemia
  • Posterolateral myocardial ischemia
  • Resting ischemia
  • Stunned myocardium

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to I25.9: its own notes plus those printed at I25, 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.

  • Ischemic heart disease (chronic) NOS

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 I25 Chronic ischemic heart disease applies to 56 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.-)

Use Additional Code

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

From I25 Chronic ischemic heart disease applies to 56 codes
  • code to identify:
  • chronic total occlusion of coronary artery (I25.82)
  • 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 I25.9, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming I25.9: they are not reported together with it, unless the two conditions are unrelated.

  • I24.9 Acute ischemic heart disease, unspecified
    ischemic heart disease (chronic) NOS (I25.9)

Excludes2 2

These codes carry an Excludes2 note naming I25.9: its condition is not part of those codes, and both may be reported when the patient has both.

  • 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

Coronary Artery Disease

Coronary artery disease (CAD) is the most common type of heart disease in the United States and a leading cause of death for both men and women.

The full article covers:

  • What is coronary artery disease?
  • What causes coronary artery disease?
  • What are the types of coronary artery disease?
  • Who is more likely to have coronary artery disease?
  • What are symptoms of coronary artery disease?
  • What other problems does coronary artery disease cause?
  • How is coronary artery disease diagnosed?
  • What are the treatments for coronary artery disease?

Read the full article at MedlinePlus

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

Convert I25.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
414.8 Chr ischemic hrt dis NEC
Approximate The match is approximate rather than exact.
ICD-9-CM
414.9 Chr ischemic hrt dis NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About I25.9Overview

What is the ICD-10 code for chronic ischemic heart disease, unspecified?

The ICD-10-CM code for chronic ischemic heart disease, unspecified is I25.9 (sometimes written as I259). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is I25.9 (Chronic ischemic heart disease) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report chronic ischemic heart disease, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does I25.9 group to?

When chronic ischemic heart disease, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 302, 303, with relative weights from 0.6610 to 1.1993 depending on complications. Higher weights mean higher Medicare reimbursement.

Does I25.9 need an additional code?

When the condition applies, yes. The Use Additional Code note at I25, which applies to I25.9, reads: code to identify: chronic total occlusion of coronary artery (I25.82); exposure to environmental tobacco smoke (Z77.22); history of tobacco dependence (Z87.891); occupational exposure to environmental tobacco smoke (Z57.31); tobacco dependence (F17.-); and 1 more listed in the Instructional Notes section. The additional code is reported after I25.9.

What is the ICD-9 equivalent of I25.9?

Under the General Equivalence Mappings, chronic ischemic heart disease, unspecified converts to ICD-9-CM 414.8 (chr ischemic hrt dis NEC) and 414.9 (chr ischemic hrt dis NOS). The mapping is approximate, so confirm the match fits the documentation.

Does I25.9 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: I25.9 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 188 (Coronary Artery Disease).