2027 ICD-10-CM Diagnosis Code I45.0Right fascicular block

ICD-10-CM Codes›I00–I99›I30-I5A›I45

ICD-10-CM I45.0
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

I45.0 is a billable ICD-10-CM diagnosis code for right fascicular block. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) 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
I45.0
Billable Status
Yes — Valid for Submission
Code Describes
Right fascicular block
Short Description
Right fascicular 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 CodeI45.0Right fascicular block

Code EditsBilling

Medicare Code Editor checks that affect claim validity for I45.0.

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.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to I45.0: its own notes plus those printed at Chapter 9. A note printed at a category, block or chapter applies to every code under it.

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 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.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

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 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 I45.0 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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About I45.0Overview

What is the ICD-10 code for right fascicular block?

The ICD-10-CM code for right fascicular block is I45.0 (sometimes written as I450). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is I45.0 (Other conduction disorders) a billable code?

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

What MS-DRG does I45.0 group to?

When right fascicular block is the principal diagnosis on an inpatient stay, it groups to MS-DRG 309, 310, 308, with relative weights from 0.5686 to 1.1809 depending on complications. Higher weights mean higher Medicare reimbursement.

Does I45.0 justify an inpatient admission?

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

What is the ICD-9 equivalent of I45.0?

Under the General Equivalence Mappings, right fascicular block converts to ICD-9-CM 426.4 (rt bundle branch block). The mapping is approximate, so confirm the match fits the documentation.