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ICD-10-CM I43: Cardiomyopathy in diseases classified elsewhere

I43 is the billable ICD-10-CM code for cardiomyopathy in diseases classified elsewhere, in category I43 (Cardiomyopathy in diseases classified elsewhere) of the Other forms of heart disease section. As a principal diagnosis it groups to MS-DRG 314 Other Circulatory System Diagnoses with MCC, MS-DRG 315 Other Circulatory System Diagnoses with CC, MS-DRG 316 Other Circulatory System Diagnoses without CC/MCC (MDC 05 MDC 05: Diseases and Disorders of the Circulatory System); or MS-DRG 791 Prematurity with Major Problems, MS-DRG 793 Full Term Neonate with Major Problems (MDC 15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period). It maps to HCC 227 (Cardiomyopathy/Myocarditis) in CMS-HCC V28. As a secondary diagnosis it is a CC, excluded with 117 principal diagnoses. 30 LCD billing and coding articles list it as covered.

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: ICD-10-CM code descriptions: FY2027 (effective October 1, 2026); IPPS Table 5 (MS-DRG weights): v44 FY2027 (final rule + CN3) (effective October 1, 2026); ICD-10-CM to HCC mapping: PY2027 initial ICD-10-CM mappings (dates of service 2026) (payment year 2027); Medicare Coverage Database billing and coding articles: MCD release October 8, 2026 (effective October 4, 2026). Next CMS release: FY2028 code files, effective October 1, 2027 for the ICD-10-CM code descriptions; FY2028 final rule (August 2027), effective October 1, 2027; an April 1 interim grouper update when CMS issues one for the IPPS Table 5 (MS-DRG weights); PY2028 advance notice (February 2027) and the PY2027 midyear final mapping (spring 2027) for the ICD-10-CM to HCC mapping; weekly, every Thursday for the Medicare Coverage Database billing and coding articles.

Code
I43
billable FY2027 ICD-10-CM code
Category
I43 Cardiomyopathy in diseases classified elsewhere
Chapter
9: Diseases of the circulatory system (I00-I99)
CC/MCC (MS-DRG v44)
CC
CMS-HCC V28
HCC 227
POA reporting
Required

Tabular list notes for I43

Excludes1 (never coded together)
  • cardiomyopathy (in):
  • coxsackie (virus) (B33.24)
  • diphtheria (A36.81)
  • sarcoidosis (D86.85)
  • tuberculosis (A18.84)
Code first
  • underlying disease, such as:
  • amyloidosis (E85.-)
  • glycogen storage disease (E74.0-)
  • gout (M10.0-)
  • thyrotoxicosis (E05.0-E05.9-)

MS-DRG grouping when I43 is the principal diagnosis

MS-DRG v44 groups for I43 as principal diagnosis
MDCMS-DRGs
05 MDC 05: Diseases and Disorders of the Circulatory System314315316
15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period791793

The final group also depends on procedures, secondary diagnoses and discharge status; the MS-DRG lookup for I43 shows the full grouping logic.

CC/MCC status and inpatient edits

As a secondary diagnosis, I43 is a CC under MS-DRG v44, unless the principal diagnosis is one of the 117 codes in its exclusion list. Check I43 against a principal diagnosis.

  • Present on admission: a POA indicator is required on inpatient claims.
  • Medicare Code Editor: manifestation code, not allowed as principal diagnosis.

CMS-HCC V28 risk adjustment

In the PY2027 mapping, I43 maps to HCC 227 (Cardiomyopathy/Myocarditis). The HCC lookup shows the RAF weight and the hierarchy.

LCD billing and coding articles that list I43

30 current Medicare billing and coding articles list I43 among the diagnoses that support medical necessity for the services they cover.

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Frequently asked questions

What does ICD-10-CM I43 mean?

I43 means cardiomyopathy in diseases classified elsewhere. It is one of 1 billable codes under I43, cardiomyopathy in diseases classified elsewhere.

What can't be coded with I43?

Excludes1 at I43: cardiomyopathy (in):; coxsackie (virus) (B33.24); diphtheria (A36.81); sarcoidosis (D86.85) and 1 more. These are never reported together with I43.

What else is coded with I43?

The tabular instructions at I43: underlying disease, such as:; amyloidosis (E85.-); glycogen storage disease (E74.0-); gout (M10.0-) and 1 more.

Which MS-DRG does I43 group to?

As the principal diagnosis, I43 groups to MS-DRG 314 Other Circulatory System Diagnoses with MCC, MS-DRG 315 Other Circulatory System Diagnoses with CC, MS-DRG 316 Other Circulatory System Diagnoses without CC/MCC (MDC 05 MDC 05: Diseases and Disorders of the Circulatory System); or MS-DRG 791 Prematurity with Major Problems, MS-DRG 793 Full Term Neonate with Major Problems (MDC 15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period) under MS-DRG v44, before procedures and secondary diagnoses are applied.

Does I43 map to an HCC?

Yes: HCC 227, Cardiomyopathy/Myocarditis, in the PY2027 CMS-HCC V28 mapping.

Is I43 a CC or MCC?

I43 is a CC under MS-DRG v44; 117 principal diagnoses exclude it.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The descriptor and notes are reproduced from the FY2027 ICD-10-CM files; MS-DRG, CC/MCC and HCC facts come from the CMS FY2027 and PY2027 tables. Code from the medical record and the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.