2026 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 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

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 2026 (October 1, 2025 through September 30, 2026) 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.

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

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

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Ischemic heart disease (chronic) NOS

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Deformity
      • artery (congenital) (peripheral) NOS
        • coronary (acquired)
    • Deformity
      • coronary artery (acquired)
    • Disease, diseased
      • heart (organic)
        • ischemic (chronic or with a stated duration of over 4 weeks)
    • Ischemia, ischemic
      • heart (chronic or with a stated duration of over 4 weeks)
    • Ischemia, ischemic
      • myocardium, myocardial (chronic or with a stated duration of over 4 weeks)
    • Ischemia, ischemic
      • supply (coronary)

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

  • Myocardial Ischemia

    a disorder of cardiac function caused by insufficient blood flow to the muscle tissue of the heart. the decreased blood flow may be due to narrowing of the coronary arteries (coronary artery disease), to obstruction by a thrombus (coronary thrombosis), or less commonly, to diffuse narrowing of arterioles and other small vessels within the heart. severe interruption of the blood supply to the myocardial tissue may result in necrosis of cardiac muscle (myocardial infarction).

Patient EducationClinical

Coronary Artery Disease

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

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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About I25.9Overview

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, 2025 through September 30, 2026.

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 0.6732 to 1.1966 depending on complications. Higher weights mean higher Medicare reimbursement.

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.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.