I42.0 ICD-10-CM Code: Dilated cardiomyopathy
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Diseases of the circulatory system (I00-I99) / Other forms of heart disease (I30-I5A)
I42.0
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceDilated cardiomyopathy
A condition where the heart muscle becomes enlarged and weakened, reducing the heart's ability to pump blood effectively throughout the body.
Buddy Insight
Dilated cardiomyopathy is a condition where the heart's main pumping chamber is enlarged and weakened, leading to reduced ejection fraction and heart failure.
CMS-HCC V28
MappedHCC 227
RAF 0.339
CMS-HCC V24
MappedHCC 85
RAF 0.368
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 85
RAF 0.0
RXHCC
MappedHCC 186
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
Official- Congestive cardiomyopathy
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 I42.0 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 I42.0 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for I42.0 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is I42.0 an HCC code?
Yes. I42.0 maps to Cardiomyopathy under the CMS-HCC V28 risk adjustment model (and Congestive Heart Failure under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.
MEAT Criteria for I42.0
For I42.0to 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 I42.0 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
I42.0 is the ICD-10-CM diagnosis code for dilated cardiomyopathy. A condition where the heart muscle becomes enlarged and weakened, reducing the heart's ability to pump blood effectively throughout the body. I42.0 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, I42.0 maps to Cardiomyopathy (HCC 227) with a community, non-dual, aged base RAF weight of 0.339. Under the older CMS-HCC V24 model, I42.0 maps to Congestive Heart Failure (HCC 85) with a community, non-dual, aged base RAF weight of 0.368. 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.
Document the ejection fraction percentage when available, as it affects severity assessment and treatment decisions. Because I42.0 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 I42.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the ejection fraction percentage when available, as it affects severity assessment and treatment decisions
- •Identify any known etiology (ischemic, idiopathic, viral) to support medical necessity
Clinical Significance
Dilated cardiomyopathy is a condition where the heart's main pumping chamber is enlarged and weakened, leading to reduced ejection fraction and heart failure. It is a leading indication for heart transplantation and carries significant mortality risk. Accurate coding reflects high resource utilization including heart failure medications, device therapy, and transplant evaluation.
Documentation Requirements
- ✓Provider diagnosis of dilated cardiomyopathy
- ✓Echocardiographic findings showing ventricular dilation and reduced systolic function
- ✓Left ventricular ejection fraction documented
- ✓Etiology if known (idiopathic, familial, viral, ischemic distinction)
- ✓Current heart failure management (medications, device therapy such as implantable cardioverter defibrillator or cardiac resynchronization therapy)
Commonly Confused Codes
- •I42.1: Obstructive hypertrophic cardiomyopathy; thickened not dilated ventricle
- •I42.9: Cardiomyopathy, unspecified; use only when the type cannot be determined
- •I50.20: Unspecified systolic (systolic) heart failure; a consequence, not the cardiomyopathy itself
- •I25.5: Ischemic cardiomyopathy; use when the dilated cardiomyopathy is due to coronary artery disease