2026 ICD-10-CM Diagnosis Code I51.5Myocardial degeneration
ICD-10-CM Codes›I00–I99›I30-I5A›I51
- Billable — Valid for Submission
- Risk Adjusts — HCC 227
- Chronic Condition
I51.5 is a billable ICD-10-CM diagnosis code for myocardial degeneration. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 314 through 316. Coders also document this condition as fatty degeneration of heart. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other and ill-defined heart disease.
For Medicare Advantage risk adjustment, I51.5 maps to CMS-HCC Category 227 (Cardiomyopathy/Myocarditis) under the V28 model, adding a risk factor of about 0.189 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
I51.5 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Fatty degeneration of heart
- Myocardial degeneration
- Myocardial disease
- Myocardial dysfunction
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Fatty degeneration of heart or myocardium
- Myocardial disease
- Senile degeneration of heart or myocardium
Type 1 Excludes
- myocardial degeneration due to hypertension I11
- myocardial degeneration due to hypertension and chronic kidney disease I13
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Cardiomalacia I51.5
Cardiomyoliposis I51.5
Disease, diseased See Also: Syndrome;
myocardium, myocardial See Also: Degeneration, myocardial; I51.5
Myocytolysis I51.5
Stricture See Also: Stenosis;
myocardium, myocardial I51.5
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Myocardial Degeneration
degeneration of myocardial tissue.
Patient EducationClinical
Cardiomyopathy
Cardiomyopathy is the name for diseases of the heart muscle. These diseases enlarge your heart muscle or make it thicker and more rigid than normal. In rare cases, scar tissue replaces the muscle tissue.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I51.5 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I51.5Overview
What is the ICD-10 code for myocardial degeneration?
The ICD-10-CM code for myocardial degeneration is I51.5 (sometimes written as I515). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is I51.5 (Complications and ill-defined descriptions of heart disease) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report myocardial degeneration on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does I51.5 group to?
When myocardial degeneration is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 315, 316, with relative weights from 0.6821 to 2.0852 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of I51.5?
Under the General Equivalence Mappings, myocardial degeneration converts to ICD-9-CM 429.1 (myocardial degeneration). The mapping is a direct match.
What HCC is I51.5?
I51.5 (myocardial degeneration) maps to CMS-HCC Category 227 (Cardiomyopathy/Myocarditis), commonly written as HCC 227, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 85 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 186.
Does I51.5 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, I51.5 adds a risk adjustment factor of about 0.189 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.145 to 0.200 depending on the payment segment). A more severe related category (HCC 221, HCC 222, HCC 223, HCC 224, HCC 225, and HCC 226) supersedes it when both are reported. See the full factor table on the HCC 227 category page.
