I42.8 ICD-10-CM Code: Other cardiomyopathies
I42.8 maps to CMS-HCC V28 227 (RAF 0.189). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC coding software
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FY 2026 Apr update / Diseases of the circulatory system (I00-I99) / Other forms of heart disease (I30-I5A)
I42.8
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther cardiomyopathies
Heart muscle disease that does not fit into the standard categories of dilated, hypertrophic, or restrictive cardiomyopathy.
Buddy Insight
This code captures cardiomyopathies that do not fit standard classifications (dilated, hypertrophic, restrictive, alcoholic, or drug-induced).
CMS-HCC V28
MappedHCC 227
RAF 0.189
CMS-HCC V24
MappedHCC 85
RAF 0.331
ACA/HHS
MappedHCC 130
Varies by metal level
ESRD/PACE
MappedHCC 85
RAF 0.063
RXHCC
MappedHCC 186
RAF 0.110
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for I42.8 in this effective period.
Excludes 2
Official- ischemic cardiomyopathy (I25.5)
- peripartum cardiomyopathy (O90.3)
- ventricular hypertrophy (I51.7)
Related Child Codes
Includes
Official- myocardiopathy
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for I42.8 in this effective period.
Code First
Official- pre-existing cardiomyopathy complicating pregnancy and puerperium (O99.4)
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for I42.8 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for I42.8 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is I42.8 an HCC code?
Yes. I42.8 (Other cardiomyopathies) maps to Cardiomyopathy/Myocarditis under the CMS-HCC V28 risk adjustment model (and Congestive Heart Failure under V24), with a community non-dual aged RAF of 0.189. It is billable for payment year 2026.
Coder answer: I42.8 is billable and maps to V28 HCC 227, Cardiomyopathy/Myocarditis. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- I42.8
- Description
- Other cardiomyopathies
- HCC (V28)
- HCC 227 — Cardiomyopathy/Myocarditis
- RAF
- 0.189
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
Work I42.8 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for I42.8
For I42.8 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed I42.8 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
I42.8 is the ICD-10-CM diagnosis code for other cardiomyopathies. Heart muscle disease that does not fit into the standard categories of dilated, hypertrophic, or restrictive cardiomyopathy. I42.8 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering other forms of heart disease (i30-i5a).
Under the CMS-HCC V28 risk adjustment model, I42.8 maps to Cardiomyopathy/Myocarditis (HCC 227) with a community, non-dual, aged base RAF weight of 0.189. Under the older CMS-HCC V24 model, I42.8 maps to Congestive Heart Failure (HCC 85) with a community, non-dual, aged base RAF weight of 0.331. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Use this code only after excluding other specific cardiomyopathy types; document the clinical presentation and any unique features. Because I42.8 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for I42.8 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only after excluding other specific cardiomyopathy types; document the clinical presentation and any unique features
- •Review the medical record for any additional diagnostic findings that might allow for a more specific cardiomyopathy classification
Clinical Significance
This code captures cardiomyopathies that do not fit standard classifications (dilated, hypertrophic, restrictive, alcoholic, or drug-induced). Examples include Takotsubo (stress) cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and noncompaction cardiomyopathy. These conditions have unique management requirements and prognostic implications.
Documentation Requirements
- ✓Provider diagnosis of a specific cardiomyopathy type not classified elsewhere
- ✓Description of the specific cardiomyopathy variant
- ✓Diagnostic evidence (echocardiogram, cardiac MRI, biopsy)
- ✓Clinical presentation and functional status
- ✓Treatment plan specific to the cardiomyopathy type
Commonly Confused Codes
- •I42.0: Dilated cardiomyopathy; use when dilation is the primary feature
- •I42.9: Cardiomyopathy, unspecified; use when the type is truly undetermined
- •I51.81: Takotsubo syndrome; now has its own specific code in recent ICD-10 updates
- •I42.5: Other restrictive cardiomyopathy; use when restriction is the dominant physiology