2026 ICD-10-CM Diagnosis Code I45.10Unspecified right bundle-branch block

ICD-10-CM Codes›I00–I99›I30-I5A›I45

ICD-10-CM I45.10
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I45.10 is a billable ICD-10-CM diagnosis code for unspecified right bundle-branch block. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 308 through 310. The code is flagged as a questionable admission, since it rarely justifies inpatient admission on its own. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Conduction disorders.

Code Identity

ICD-10-CM Code
I45.10
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified right bundle-branch block
Short Description
Unspecified right bundle-branch block
Same as the full description in the CMS dataset.
Parent Code
I45.1
Other and unspecified right bundle-branch block

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI45Other conduction disorders
This CodeI45.10Unspecified right bundle-branch block

Code EditsBilling

Medicare Code Editor checks that affect claim validity for I45.10.

Questionable admission codes
Some diagnoses are not usually sufficient justification for admission to an acute care hospital. For example, if a patient is given code R030 for elevated blood pressure reading, without diagnosis of hypertension, then the patient would have a questionable admission, since elevated blood pressure reading is not normally sufficient justification for admission to a hospital. The following list contains diagnosis codes identified as questionable admission when used.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bifascicular block
  • Bifascicular block on electrocardiogram
  • Brugada electrocardiograph pattern
  • EKG: complete right bundle branch block
  • EKG: Incomplete right bundle branch block
  • EKG: left bundle branch block
  • EKG: right bundle branch block
  • Left anterior fascicular block
  • Left anterior fascicular block on electrocardiogram
  • Monofascicular block
  • Right bundle branch block
  • Right bundle branch block AND left anterior fascicular block
  • Right bundle branch block and left anterior fascicular block on electrocardiogram
  • Right bundle branch block with left bundle branch block
  • Right bundle branch block, anterior fascicular block AND incomplete posterior fascicular block
  • Spontaneous Brugada electrocardiograph pattern

Tabular List NotesGuidance

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

Inclusion Terms

  • Right bundle-branch block 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.

    • Block, blocked
      • bundle-branch (complete) (false) (incomplete)
        • right

Clinical ClassificationClinical

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

CCSR CIR016
Conduction disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Arrhythmia

An arrhythmia is a problem with the rate or rhythm of your heartbeat. Your heart beats too quickly, too slowly, or with an irregular pattern. Changes in the electrical signals that control your heartbeat cause arrhythmias.

The full article covers:

  • What is an arrhythmia?
  • What causes an arrhythmia?
  • What are the symptoms of an arrhythmia?
  • How is an arrhythmia diagnosed?
  • What are the treatments for an arrhythmia?
  • Can arrhythmias be prevented?

Read the full article at MedlinePlus

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

Convert I45.10 to ICD-9-CMHistory

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

ICD-9-CM
426.4 Rt bundle branch block
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 I45.10Overview

Is I45.10 (Other and unspecified right bundle-branch block) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified right bundle-branch block on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I45.10 group to?

When unspecified right bundle-branch block is the principal diagnosis on an inpatient stay, it groups to MS-DRG 308, 309, 310, with relative weights from 0.5661 to 1.2040 depending on complications. Higher weights mean higher Medicare reimbursement.

Does I45.10 justify an inpatient admission?

Not on its own. The Medicare Code Editor lists this code as a questionable admission because unspecified right bundle-branch block is not usually sufficient justification for admission to an acute care hospital.

What is the ICD-9 equivalent of I45.10?

Under the General Equivalence Mappings, unspecified right bundle-branch block converts to ICD-9-CM 426.4 (rt bundle branch block). 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.