2027 ICD-10-CM Diagnosis Code I42.81Arrhythmogenic cardiomyopathy

ICD-10-CM Codes›I00–I99›I30-I5A›I42

ICD-10-CM I42.81
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

I42.81 is a billable ICD-10-CM diagnosis code for arrhythmogenic cardiomyopathy. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 314 through 316. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 117 closely related codes. Coders also document this condition as arrhythmogenic left ventricular cardiomyopathy.

Code Identity

ICD-10-CM Code
I42.81
Billable Status
Yes — Valid for Submission
Code Describes
Arrhythmogenic cardiomyopathy
Short Description
Arrhythmogenic cardiomyopathy
Same as the full description in the CMS dataset.
Parent Code
I42.8
Other cardiomyopathies

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI42Cardiomyopathy
This CodeI42.81Arrhythmogenic cardiomyopathy

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Arrhythmogenic left ventricular cardiomyopathy
  • Arrhythmogenic right ventricular dysplasia
  • Autosomal recessive familial wooly hair
  • Congenital wooly hair
  • Familial isolated arrhythmogenic right ventricular dysplasia
  • Naxos disease

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to I42.81: its own notes plus those printed at I42 and Chapter 9. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From I42 Cardiomyopathy applies to 13 codes
  • myocardiopathy

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 I42 Cardiomyopathy applies to 13 codes
  • ischemic cardiomyopathy (I25.5)
  • peripartum cardiomyopathy (O90.3)
  • ventricular hypertrophy (I51.7)
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.-)

Code First

The underlying condition named in the note is sequenced before this code.

From I42 Cardiomyopathy applies to 13 codes
  • pre-existing cardiomyopathy complicating pregnancy and puerperium (O99.4)

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

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name I42.81, its category, or a range that includes it.

Applicable To 1

These notes mention I42.81.

  • O90.3 Peripartum cardiomyopathy
    Conditions in I42.- arising during pregnancy and the puerperium names I42.-, which includes this code

Code First 1

These codes say to code first a condition named in the note, and I42.81 is one of the conditions named.

  • I5A Non-ischemic myocardial injury (non-traumatic)
    cardiomyopathy (I42.-) names I42.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical InformationClinical

  • Cardiomyopathies

    a group of diseases in which the dominant feature is the involvement of the cardiac muscle itself. cardiomyopathies are classified according to their predominant pathophysiological features (dilated cardiomyopathy; hypertrophic cardiomyopathy; restrictive cardiomyopathy) or their etiological/pathological factors (cardiomyopathy, alcoholic; endocardial fibroelastosis).

Code History & ChangesHistory

New Code I42.81 was added to the ICD-10-CM code set for FY 2027, effective October 1, 2026.

Replacement I42.81 replaces the following previously assigned code(s):

  • I42.8 - Other cardiomyopathies
FY 2027AddedAdded to the ICD-10-CM code setEffective October 1, 2026.
FY 2027CurrentRevised in the current code setEffective October 1, 2026 through September 30, 2027.

Questions About I42.81Overview

What is the ICD-10 code for arrhythmogenic cardiomyopathy?

The ICD-10-CM code for arrhythmogenic cardiomyopathy is I42.81 (sometimes written as I4281). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is I42.81 (Other cardiomyopathies) a billable code?

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

What MS-DRG does I42.81 group to?

When arrhythmogenic cardiomyopathy is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 316, 315, with relative weights from 0.6678 to 2.0871 depending on complications. Higher weights mean higher Medicare reimbursement.

Is I42.81 a CC or MCC?

CMS lists I42.81 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 117 closely related codes in its exclusion list.

What is coded first with I42.81?

The Code First note at I42, which applies to I42.81, reads: pre-existing cardiomyopathy complicating pregnancy and puerperium (O99.4). When one of these applies, it is sequenced before I42.81.