What is ICD-10 code I43?

I43 is the ICD-10-CM diagnosis code for Cardiomyopathy in diseases classified elsewhere. It belongs to the ICD-10-CM chapter for diseases of the circulatory system (i00-i99). I43 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. I43 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. I43 is a payment HCC under the CMS risk adjustment model. Under the CMS-HCC V28 risk adjustment model it maps to Cardiomyopathy/Myocarditis with a community, non-dual, aged base RAF weight of 0.189. Under the older CMS-HCC V24 model it maps to Congestive Heart Failure at RAF 0.331. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. HCC Buddy maintains the V28 and V24 mapping, RAF weight, and MEAT documentation criteria for I43 sourced directly from the CMS-HCC model files.

Yes. I43 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. I43 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for I43?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For I43, V28 maps to Cardiomyopathy/Myocarditis at RAF 0.189 while V24 mapped to Congestive Heart Failure at RAF 0.331. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting I43?

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 Because I43 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

I43: Cardiomyopathy in diseases classified elsewhere — ICD-10 | Cardiomyopathy/Myocarditis

ICD-10-CM Code View

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Code lookupI43Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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 guidance

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.

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

Mapped

HCC 227

Cardiomyopathy/Myocarditis

RAF 0.189

CMS-HCC V24

Mapped

HCC 85

Congestive Heart Failure

RAF 0.331

ACA/HHS

Mapped

HCC 130

HHS-HCC 130

Varies by metal level

ESRD/PACE

Mapped

HCC 85

Congestive Heart Failure

RAF 0.063

RXHCC

Mapped

HCC 186

Heart Failure

RAF 0.110

Code Book Path

Official

I4Other forms of heart disease (I30-I5A)

I43Cardiomyopathy in diseases classified elsewhere

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for I43 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for I43 in this effective period.

Related Child Codes

Official

ICD-10-CM does not list child codes under I43 for this display context.

Includes

Official

ICD-10-CM does not list Includes notes for I43 in this effective period.

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

Official

ICD-10-CM does not list Use Additional Code instructions for I43 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for I43 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

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

MEAT Support

HCC Buddy guidance

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

Audit Caution

HCC Buddy guidance

Using this code without coding the underlying primary disease first — it is a mandatory secondary code

Confusing with primary cardiomyopathy codes (I42 series) — I43 specifically requires an underlying disease

Not verifying that the causal relationship between the disease and cardiomyopathy is documented

Failing to sequence the underlying disease code before this manifestation code

Common Mistakes

HCC Buddy guidance

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

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 I43 an HCC code?

Yes. I43 maps to Cardiomyopathy/Myocarditis under the CMS-HCC V28 risk adjustment model (and Congestive Heart Failure under V24).

HCC Category Mapping

V28HCC 227, Cardiomyopathy/Myocarditis

0.189

V24HCC 85, Congestive Heart Failure

0.331

ESRDHCC 85, Congestive Heart Failure

0.063

RxHCCHCC 186, Heart Failure

0.110

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 I43 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for I43

For I43to 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 I43 during that encounter, not just copy-forwarded from a problem list.

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 community, non-dual, aged base RAF weight of 0.189. Under the older CMS-HCC V24 model, I43 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.

This is a secondary diagnosis code that requires documentation of the underlying disease causing the cardiomyopathy; always code the primary condition first. Because I43 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 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

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-)

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

Code Hierarchy

└I43Cardiomyopathy in diseases classified elsewhere

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

HCC Buddy Code Card

I43

Is I43 an HCC code?

HCC Category Mapping

MEAT Criteria for I43

Get the V28 RAF + MEAT cheat sheet

What This Code Means

Coding Tips

Clinical Significance

Documentation Requirements

Excludes 1, Do NOT code together

Code First

Commonly Confused Codes

Code Hierarchy

Work I43 in HCC Buddy