I43 ICD-10-CM Code: Cardiomyopathy in diseases classified elsewhere
I43 maps to CMS-HCC V28 227. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools
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FY 2026 Apr update / Diseases of the circulatory system (I00-I99) / Other forms of heart disease (I30-I5A)
I43
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceCardiomyopathy in diseases classified elsewhere
This code is used when the heart muscle becomes weakened or enlarged as a result of another disease or condition that the patient has. It indicates that cardiomyopathy (a problem with the heart's pumping ability) is secondary to another underlying medical condition rather than being a primary heart disease.
Buddy Insight
Cardiomyopathy in diseases classified elsewhere is a manifestation code indicating that heart muscle disease has developed secondary to another primary condition.
CMS-HCC V28
MappedHCC 227
Coefficient HCC 227: 0.189 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 130
Code-level coefficient reference
ESRD/PACE
MappedHCC 85
Code-level coefficient reference
RXHCC
MappedHCC 186
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for I43. Check the code and parent instructions in the Code Book.
Excludes 2
Official- certain conditions originating in the perinatal period (P04-P96)Inherited from I00-I99
- certain infectious and parasitic diseases (A00-B99)Inherited from I00-I99
- complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from I00-I99
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Inherited from I00-I99
- endocrine, nutritional and metabolic diseases (E00-E88)Inherited from I00-I99
- injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from I00-I99
- neoplasms (C00-D49)Inherited from I00-I99
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from I00-I99
- systemic connective tissue disorders (M30-M36)Inherited from I00-I99
- transient cerebral ischemic attacks and related syndromes (G45.-)Inherited from I00-I99
Related Codes
No related codes are included in this display for I43. Check the Code Book for the complete code path.
Includes
OfficialNo Includes notes are included in this display for I43. Check the code and parent instructions in the Code Book.
Excludes 1
Official- cardiomyopathy (in):
- coxsackie (virus) (B33.24)
- diphtheria (A36.81)
- sarcoidosis (D86.85)
- tuberculosis (A18.84)
Code First
Official- underlying disease, such as:
- amyloidosis (E85.-)
- glycogen storage disease (E74.0-)
- gout (M10.0-)
- thyrotoxicosis (E05.0-E05.9-)
Use Additional
OfficialNo Use Additional Code instructions are included in this display for I43. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for I43. Check the code and parent instructions in the Code Book.
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 I43 an HCC code?
Yes. I43 (Cardiomyopathy in diseases classified elsewhere) maps to HCC 227, Cardiomyopathy/Myocarditis under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.189. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: I43 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
- I43
- Description
- Cardiomyopathy in diseases classified elsewhere
- HCC (V28)
- HCC 227 — Cardiomyopathy/Myocarditis
- RAF reference coefficient
- 0.189
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work I43 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for I43
For I43, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- 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
Coder workflow notes
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What This Code Means
I43 is the ICD-10-CM diagnosis code for cardiomyopathy in diseases classified elsewhere. This code is used when the heart muscle becomes weakened or enlarged as a result of another disease or condition that the patient has. It indicates that cardiomyopathy (a problem with the heart's pumping ability) is secondary to another underlying medical condition rather than being a primary heart disease. I43 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, I43 maps to Cardiomyopathy/Myocarditis (HCC 227) with a source-labeled community, non-dual, aged reference coefficient of 0.189. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
This is a secondary diagnosis code that requires documentation of the underlying disease causing the cardiomyopathy; always code the primary condition first. For I43, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for I43 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a secondary diagnosis code that requires documentation of the underlying disease causing the cardiomyopathy; always code the primary condition first
- •Do not use this code for primary cardiomyopathy (I42.-); verify the causal relationship between the documented disease and cardiomyopathy is clearly stated in the medical record
Clinical Significance
Cardiomyopathy in diseases classified elsewhere is a manifestation code indicating that heart muscle disease has developed secondary to another primary condition. Common underlying causes include thyrotoxicosis, hemochromatosis, and metabolic disorders. This code captures the cardiac consequence of systemic disease and must always be paired with the underlying etiology code.
Documentation Requirements
- ✓Provider diagnosis of cardiomyopathy as a manifestation of another disease
- ✓Underlying primary disease documented and coded first
- ✓Causal relationship between the primary disease and cardiomyopathy explicitly stated
- ✓Echocardiographic or other evidence of cardiac dysfunction
- ✓Documentation that the cardiomyopathy is secondary, not primary
Excludes 1, Do NOT code together
Code First
Commonly Confused Codes
- •I42.0-I42.9: Primary cardiomyopathy codes; use for primary heart muscle disease, not secondary
- •I42.7: Cardiomyopathy due to drug and external agent; for external causes, not underlying diseases
- •I42.6: Alcoholic cardiomyopathy; specific etiology with its own code
- •I42.8: Other cardiomyopathies; for primary cardiomyopathies not otherwise classified