Alphabetic Index FY2027

I42.00

Dilated cardiomyopathy, unspecified

FY2027Chapter 9: Diseases of the circulatory system/I30–I5A Other forms of heart disease

BillableComplete code, valid to report
Care settingsHospital CCIPF Comorbidity · Cardiac Conditions

I42.00 (also written I4200) is a billable ICD-10-CM diagnosis code for dilated cardiomyopathy, unspecified. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 13 codes in category I42 (Cardiomyopathy). The Alphabetic Index lists it under 2 entries. Its coding notes include a Code first instruction and 13 Excludes2 entries.

Code first

If the underlying condition listed here is present and known, sequence it first.

Inherited from I42 Cardiomyopathy
  • pre-existing cardiomyopathy complicating pregnancy and puerperium (O99.4)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Inherited from I42 Cardiomyopathy
  • ischemic cardiomyopathy (I25.5)
  • peripartum cardiomyopathy (O90.3)
  • ventricular hypertrophy (I51.7)
Also from chapter/block level (10 notes)
Inherited from Chapter 9 Diseases of the circulatory system
  • 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.-)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Hospital CC

Counts as a complication or comorbidity (CC) when reported as a secondary diagnosis on an inpatient claim. It does not count when the principal diagnosis is one of the 117 codes in its exclusion list. Some MS-DRGs also ignore a CC or MCC that defines the DRG.

Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix C

IPF Comorbidity

On the CMS IPF comorbidity list.

Comorbidity categoryFactor
Cardiac Conditions1.04
It counts as a comorbidity when reported as a secondary diagnosis and actively treated during the stay. An IPF receives only one adjustment within a category and can receive adjustments in more than one category.

Source: CMS IPF PPS FY 2027 final rule (CMS-1847-F), Addendum B-3 (comorbidity codes with adjustment factor); effective for discharges on or after October 1, 2026

Includes

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

Inherited from I42 Cardiomyopathy
  • myocardiopathy

Inclusion terms

Conditions classified to this code.

This code
  • Congestive cardiomyopathy, NOS

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 2 entries