2026 ICD-10-CM Diagnosis Code I45.3Trifascicular block

ICD-10-CM Codes›I00–I99›I30-I5A›I45

ICD-10-CM I45.3
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I45.3 is a billable ICD-10-CM diagnosis code for trifascicular 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. Coders also document this condition as right bundle branch block with left bundle branch block. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Conduction disorders.

Code Identity

ICD-10-CM Code
I45.3
Billable Status
Yes — Valid for Submission
Code Describes
Trifascicular block
Short Description
Trifascicular block
Same as the full description in the CMS dataset.
Parent Code
I45
Other conduction disorders

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI45Other conduction disorders
This CodeI45.3Trifascicular block

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Right bundle branch block with left bundle branch block
  • Trifascicular block
  • Trifascicular block on electrocardiogram

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
      • trifascicular

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 I45.3 to ICD-9-CMHistory

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

ICD-9-CM
426.54 Trifascicular block
Exact Match The mapping is direct, with no qualifiers.

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 I45.3Overview

Is I45.3 (Other conduction disorders) a billable code?

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

What MS-DRG does I45.3 group to?

When trifascicular 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.

What is the ICD-9 equivalent of I45.3?

Under the General Equivalence Mappings, trifascicular block converts to ICD-9-CM 426.54 (trifascicular block). The mapping is a direct match.

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.