2027 ICD-10-CM Diagnosis Code I45.9Conduction disorder, unspecified

ICD-10-CM Codes›I00–I99›I30-I5A›I45

ICD-10-CM I45.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

I45.9 is a billable ICD-10-CM diagnosis code for conduction disorder, unspecified. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Conduction disorders.

Code Identity

ICD-10-CM Code
I45.9
Billable Status
Yes — Valid for Submission
Code Describes
Conduction disorder, unspecified
Short Description
Conduction disorder, unspecified
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 CodeI45.9Conduction disorder, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Aberrantly conducted complex
  • Abnormal cardiac conduction
  • Atrial septal defect, atrioventricular conduction defect syndrome
  • Cardiac syncope
  • Conduction disorder of the heart
  • Congenital conduction defect
  • EKG: heart block
  • Heart block
  • Heart block caused by drug
  • Malfunction from artificial pacing
  • Microcephalus, cerebellar hypoplasia, cardiac conduction defect syndrome
  • Neurodevelopmental delay, hypotonia, cerebellar ataxia, cardiac conduction defects syndrome
  • Paroxysmal atrial tachycardia with block
  • Rhythm from artificial pacing
  • Stokes-Adams attack

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to I45.9: its own notes plus those printed at 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.

  • Heart block NOS
  • Stokes-Adams syndrome

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.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name I45.9, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming I45.9: they are not reported together with it, unless the two conditions are unrelated.

  • I45.5 Other specified heart block
    heart block NOS (I45.9)
  • R55 Syncope and collapse
    Stokes-Adams attack (I45.9)

Code Also 1

These codes say I45.9 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • H49.81 Kearns-Sayre syndrome
    heart block (I45.9)

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

Clinical InformationClinical

  • Cardiac Conduction Disorder

    a disorder affecting the conduction system that sends electrical signals in the myocardium.

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 I45.9 to ICD-9-CMHistory

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

ICD-9-CM
426.9 Conduction disorder NOS
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About I45.9Overview

What is the ICD-10 code for conduction disorder, unspecified?

The ICD-10-CM code for conduction disorder, unspecified is I45.9 (sometimes written as I459). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is I45.9 (Other conduction disorders) a billable code?

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

What MS-DRG does I45.9 group to?

When conduction disorder, unspecified 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.

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

Under the General Equivalence Mappings, conduction disorder, unspecified converts to ICD-9-CM 426.9 (conduction disorder NOS). The mapping is a direct match.