ICD-10 · PDGM grouping
I42 Cardiomyopathy
All 13 codes in the I42 family, with the PDGM clinical group, comorbidity subgroup and primary-position rule CMS assigns, read from the CMS grouper crosswalk v07.2.26 and the CDC FY2027 code file.
Codes in family
13
Can lead a claim
12
Cannot lead a claim
1
What CMS assigns to I42
12 of the 13 codes group to MMTA - Cardiac and Circulatory; 1 is assigned no clinical group. None of the 13 is assigned a comorbidity subgroup. 12 of the 13 can lead a claim. CMS attaches a code-first note to all 13.
Code first
CMS grouper convention 68, on I42.00, I42.01, I42.09, I42.1, I42.2, I42.3, I42.4, I42.5, I42.6, I42.81, I42.89, I42.9. Code first:
- pre-existing cardiomyopathy complicating pregnancy and puerperium (O99.4)
CMS grouper convention 69, on I42.7. Code first:
- poisoning due to drug or toxin, if applicable (T36-T65 with fifth or sixth character 1-4)
- pre-existing cardiomyopathy complicating pregnancy and puerperium (O99.4)
Every code in I42
Descriptions are CDC’s FY2027 wording; where CMS’s grouper abbreviates one, its form is shown beneath.
| Code | Description | Primary position | Clinical group | Comorbidity subgroup |
|---|---|---|---|---|
| I42.0 Dilated cardiomyopathy | ||||
| I42.00 | Dilated cardiomyopathy, unspecified | Cannot lead a claimPrincipal diagnosis not assigned to a clinical group | None | None |
| I42.01 | Familial-genetic dilated cardiomyopathy | Can lead a claim, code first applies | H | None |
| I42.09 | Other dilated cardiomyopathy | Can lead a claim, code first applies | H | None |
| I42.1 | Obstructive hypertrophic cardiomyopathy | Can lead a claim, code first applies | H | None |
| I42.2 | Other hypertrophic cardiomyopathy | Can lead a claim, code first applies | H | None |
| I42.3 | Endomyocardial (eosinophilic) disease | Can lead a claim, code first applies | H | None |
| I42.4 | Endocardial fibroelastosis | Can lead a claim, code first applies | H | None |
| I42.5 | Other restrictive cardiomyopathy | Can lead a claim, code first applies | H | None |
| I42.6 | Alcoholic cardiomyopathy | Can lead a claim, code first applies | H | None |
| I42.7 | Cardiomyopathy due to drug and external agent | Can lead a claim, code first applies | H | None |
| I42.8 Other cardiomyopathies | ||||
| I42.81 | Arrhythmogenic cardiomyopathy | Can lead a claim, code first applies | H | None |
| I42.89 | Other cardiomyopathies not elsewhere classified | Can lead a claim, code first applies | H | None |
| I42.9 | Cardiomyopathy, unspecified | Can lead a claim, code first applies | H | None |
Sources: CMS HH PPS Grouper Software v07.2.26, effective 2026-10-01, for the clinical group, comorbidity subgroup, code-first conventions and primary-position flags; CDC NCHS ICD-10-CM FY2027 code descriptions for the family title and code wording. This is the crosswalk Medicare runs a claim through. Grouping also depends on admission source, timing, the OASIS functional items and the rest of the diagnosis list.
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