ICD-10-CM 2027 diagnosis code
I45.9Conduction disorder, unspecified
I45.9 is a valid, billable ICD-10-CM code for conduction disorder, unspecified. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Looking up by condition? See ICD-10 code for Heart block, ICD-10 code for Spens' syndrome, ICD-10 code for Dropped heart beats, ICD-10 code for Morgagni-Stokes-Adams syndrome.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About I45.9
I45.9 is the ICD-10-CM diagnosis code for conduction disorder, unspecified. It belongs to category I45 (other conduction disorders), block I30-I5A (other forms of heart disease) and chapter 9 (diseases of the circulatory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within I45, choose I45.9 (Conduction disorder, unspecified) only when documentation doesn't support a more specific option: right fascicular block (I45.0), other and unspecified right bundle-branch block (I45.1), Bifascicular block (I45.2), Trifascicular block (I45.3), nonspecific intraventricular block (I45.4), other specified heart block (I45.5), Pre-excitation syndrome (I45.6) and other specified conduction disorders (I45.8).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 308 (Cardiac Arrhythmia and Conduction Disorders with MCC, relative weight 1.1806), DRG 309 (Cardiac Arrhythmia and Conduction Disorders with CC, relative weight 0.7316) and DRG 310 (Cardiac Arrhythmia and Conduction Disorders without CC/MCC, relative weight 0.568), in MDC 05 (Diseases and Disorders of the Circulatory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 426.9 (conduction disorder, unspecified).
Coding notes
- Heart block NOS
- Stokes-Adams syndrome
Notes that apply from higher levels
Instructions written at a parent level also apply to I45.9.
Broader instructions also apply from Chapter 9: Diseases of the circulatory system.
Alphabetic index entries
22 entriesTerms in the official ICD-10-CM index that lead to I45.9.
- Adams-Stokes (-Morgagni) disease or syndrome
- Arrhythmia (auricle)(cardiac)(juvenile)(nodal)(reflex)(supraventricular)(transitory)(ventricle) › block
- Attack, attacks › Adams-Stokes
- Attack, attacks › Stokes-Adams
- Block, blocked › arrhythmic
- Block, blocked › cardiac
- Block, blocked › conduction
- Block, blocked › heart
- Defect, defective › conduction (heart)
- Delay, delayed › conduction (cardiac) (ventricular)
- Disease, diseased › Adams-Stokes (-Morgagni) (syncope with heart block)
- Disease, diseased › Morgagni-Adams-Stokes (syncope with heart block)
- Disease, diseased › Stokes-Adams (syncope with heart block)
- Disorder (of) › conduction, heart
- Dropped heart beats
- Morgagni-Stokes-Adams syndrome
- Spens' syndrome (syncope with heart block)
- Stokes-Adams disease or syndrome
- Syndrome › Adams-Stokes (-Morgagni)
- Syndrome › Morgagni-Adams-Stokes
- Syndrome › Spen's
- Syndrome › Stokes (-Adams)
Codes whose notes reference I45.9
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 05 · Diseases and Disorders of the Circulatory System
ICD-9-CM equivalent
Converter →- 426.9Conduction disorder, unspecifiedexact
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about I45.9
Is I45.9 billable?
- Yes. I45.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I45.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict I45.9 as a principal diagnosis.
Is I45.9 a CC or MCC?
- No. I45.9 is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does I45.9 group to?
- I45.9 is used in the MS-DRG v44.0 logic for MS-DRG 308 (Cardiac Arrhythmia and Conduction Disorders with MCC), MS-DRG 309 (Cardiac Arrhythmia and Conduction Disorders with CC) and MS-DRG 310 (Cardiac Arrhythmia and Conduction Disorders without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for I45.9?
- The CMS General Equivalence Mappings map I45.9 to ICD-9-CM 426.9.