2026 ICD-10-CM Diagnosis Code I42.2Other hypertrophic cardiomyopathy

ICD-10-CM Codes›I00–I99›I30-I5A›I42

ICD-10-CM I42.2
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I42.2 is a billable ICD-10-CM diagnosis code for other hypertrophic cardiomyopathy. 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. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 112 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Myocarditis and cardiomyopathy.

For Medicare Advantage risk adjustment, I42.2 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

ICD-10-CM Code
I42.2
Billable Status
Yes — Valid for Submission
Code Describes
Other hypertrophic cardiomyopathy
Short Description
Other hypertrophic cardiomyopathy
Same as the full description in the CMS dataset.
Parent Code
I42
Cardiomyopathy

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI42Cardiomyopathy
This CodeI42.2Other hypertrophic cardiomyopathy

Medicare Risk Adjustment (HCC)Billing

I42.2 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.

CMS-HCC V28 Category (Payment Model)
HCC 227— Cardiomyopathy/Myocarditis
Payment HCC · PY 2026 one of 14 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.189
community, non-dual, aged · ranges 0.145–0.200 across segments
Hierarchy
Superseded by HCC 221, HCC 222, HCC 223, HCC 224, HCC 225, and HCC 226
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 85
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 85 · ESRD (V21): HCC 85 · ESRD (V24): HCC 85
ESRD V21 weights: 0.082 dialysis, 0.186–0.336 functioning graft · ESRD V24 weights: 0.063 dialysis, 0.169–0.302 functioning graft
Part D (RxHCC)
RxHCC 186 — Heart Failure
also risk-adjusts in the Part D prescription drug model (V08)

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.

  • Apical hypertrophic cardiomyopathy
  • Apical hypertrophic cardiomyopathy with aneurysm
  • Cardiomyopathy due to storage disease
  • Cardiomyopathy in Friedreich's ataxia
  • Familial cardiomyopathy
  • Fatal congenital hypertrophic cardiomyopathy due to glycogen storage disease
  • Hypertrophic cardiomyopathy
  • Hypertrophic cardiomyopathy and renal tubular disease due to mitochondrial DNA mutation
  • Hypertrophic cardiomyopathy due to disorder
  • Hypertrophic cardiomyopathy due to Friedreich ataxia
  • Hypertrophic cardiomyopathy due to glycogen storage disease
  • Hypertrophic cardiomyopathy due to hyperthyroidism
  • Hypertrophic cardiomyopathy due to lysosomal disease
  • Hypertrophic cardiomyopathy due to neuromuscular disorder
  • Hypertrophic cardiomyopathy with genetic marker
  • Hypertrophic cardiomyopathy with hypotonia and lactic acidosis syndrome
  • Hypertrophic cardiomyopathy without obstruction
  • Hypertrophic mitochondrial cardiomyopathy
  • Hypertrophic mitochondrial cardiomyopathy associated with cataracts and lactic acidosis
  • Infantile hypertrophic cardiomyopathy due to MRPL44 deficiency
  • Left ventricular aneurysm
  • Mitochondrial hypertrophic cardiomyopathy with lactic acidosis due to MTO1 deficiency
  • Primary familial hypertrophic cardiomyopathy
  • Primary hypertrophic cardiomyopathy
  • Primary idiopathic hypertrophic cardiomyopathy
  • Progressive sensorineural hearing loss and hypertrophic cardiomyopathy syndrome

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Nonobstructive hypertrophic cardiomyopathy

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR005
Myocarditis and cardiomyopathy
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Apical Hypertrophic Cardiomyopathy

    a hypertrophic cardiomyopathy characterized by apical hypertrophy, typically left ventricular hypertrophy (described as ace of spades sign), and deep t-wave inversions in ekg. clinical symptoms include minor symptoms such as chest pain; dyspnea; and syncope to more complex symptoms such as atrial fibrillation; ventricular fibrillation; myocardial infarction and congestive heart failure. a transient left ventricular apical hypertrophy is sometimes associated with takotsubo cardiomyopathy.

  • Familial Hypertrophic Cardiomyopathy Type 1|Asymmetric Septal Hypertrophy|CMH1|Hereditary Ventricular Hypertrophy|IHSS|Idiopathic Hypertrophic Subaortic Stenosis

    an autosomal dominant subtype of familial hypertrophic cardiomyopathy caused by mutation(s) in the cav3 gene, myh7 gene, or mylk2 gene encoding caveolin-3, myosin heavy chain 7, and myosin light chain kinase 2, skeletal/cardiac muscle respectively.

  • Familial Hypertrophic Cardiomyopathy Type 11|CMH11

    an autosomal dominant subtype of familial hypertrophic cardiomyopathy caused by mutation(s) in the actc1 gene, encoding actin, alpha cardiac muscle 1.

  • Familial Hypertrophic Cardiomyopathy Type 14|CMH14

    an autosomal dominant subtype of familial hypertrophic cardiomyopathy caused by mutation(s) in the myh6 gene, encoding myosin-6.

  • Familial Hypertrophic Cardiomyopathy Type 17|CMH17

    an autosomal dominant subtype of familial hypertrophic cardiomyopathy caused by mutation(s) in the jph2 gene, encoding junctophilin-2.

  • Familial Hypertrophic Cardiomyopathy Type 2|CMH2

    an autosomal dominant subtype of familial hypertrophic cardiomyopathy caused by mutation(s) in the tnnt2 gene, encoding troponin t, cardiac muscle.

  • Familial Hypertrophic Cardiomyopathy Type 26|CMH26

    an autosomal dominant subtype of familial hypertrophic cardiomyopathy caused by mutation(s) in the flnc gene, encoding filamin-c.

  • Familial Hypertrophic Cardiomyopathy Type 27|CMH27

    an autosomal recessive subtype of familial hypertrophic cardiomyopathy caused by mutation(s) in the alpk3 gene, encoding alpha-protein kinase 3.

  • Familial Hypertrophic Cardiomyopathy Type 3|CMH3

    an autosomal dominant subtype of familial hypertrophic cardiomyopathy caused by mutation(s) in the tpm1 gene, encoding tropomyosin alpha-1 chain.

  • Familial Hypertrophic Cardiomyopathy Type 4|CMH4

    an autosomal dominant condition caused by mutation(s) in the mybpc3 gene, encoding mybpc3 protein. it is characterized by severe neonatal hypertrophic cardiomyopathy.

  • Familial Hypertrophic Cardiomyopathy Type 6|CMH6

    an autosomal dominant subtype of familial hypertrophic cardiomyopathy caused by mutation(s) in the prkag2 gene, encoding 5'-amp-activated protein kinase subunit gamma-2.

  • Familial Hypertrophic Cardiomyopathy Type 7|CMH7

    an autosomal dominant subtype of familial hypertrophic cardiomyopathy caused by mutation(s) in the tnni3 gene, encoding troponin i, cardiac muscle.

  • Familial Hypertrophic Cardiomyopathy|Hypertrophic Familial Cardiomyopathy

    hypertrophic cardiomyopathy caused by mutations in the genes encoding components of the sarcomere, in the absence of predisposing conditions.

  • Hypertrophic Cardiomyopathy

    a condition in which the myocardium is hypertrophied without an obvious cause. the hypertrophy is generally asymmetric and may be associated with obstruction of the ventricular outflow tract.

  • Left Ventricular Aneurysm

    a bulge or ballooning in the wall of the left ventricle of the heart.

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 I42.2 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
425.18 Oth hyprtrophic cardiomy
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About I42.2Overview

What is the ICD-10 code for other hypertrophic cardiomyopathy?

The ICD-10-CM code for other hypertrophic cardiomyopathy is I42.2 (sometimes written as I422). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is I42.2 (Cardiomyopathy) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other hypertrophic cardiomyopathy on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I42.2 group to?

When other hypertrophic cardiomyopathy 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.

Is I42.2 a CC or MCC?

CMS lists I42.2 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 112 closely related codes in its exclusion list.

What is the ICD-9 equivalent of I42.2?

Under the General Equivalence Mappings, other hypertrophic cardiomyopathy converts to ICD-9-CM 425.18 (oth hyprtrophic cardiomy). The mapping is a direct match.

What HCC is I42.2?

I42.2 (other hypertrophic cardiomyopathy) 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 I42.2 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, I42.2 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.