2025 ICD-10-CM Diagnosis Code I42.4

Endocardial fibroelastosis

• I42.4 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
• The 2025 edition of ICD-10-CM I42.4 became effective on October 1, 2024.
• This is the American ICD-10-CM version of I42.4 – other international versions of ICD-10 I42.4 may differ.

Applicable To

• Congenital cardiomyopathy
• Elastomyofibrosis

The following code(s) above I42.4 contain annotation back-references

 that may be applicable to I42.4:

• I00-I99  Diseases of the circulatory system
• I42  Cardiomyopathy

Approximate Synonyms

• Arrhythmogenic right ventricular dysplasia
• Cardiomyopathy restrictive, endocardial fibroelastosis
• Congenital arrhythmogenic right ventricular dysplasia
• Congenital endocardial fibroelastosis (at birth)
• Primary endocardial fibroelastosis
• Primary endocardial fibroelastosis (heart condition)
• Restrictive cardiomyopathy secondary to endocardial fibroelastosis

Clinical Information

• A condition characterized by the thickening of endocardium due to proliferation of fibrous and elastic tissue, usually in the left ventricle leading to impaired cardiac function (cardiomyopathy, restrictive). It is most commonly seen in young children and rarely in adults. It is often associated with congenital heart anomalies (heart defects congenital;) infection; or gene mutation. Defects in the tafazzin protein, encoded by taz gene, result in a form of autosomal dominant familial endocardial fibroelastosis.
• A rare disorder characterized by diffuse thickening of the endocardium. It presents with unexplained heart failure.
• Condition characterized by hypertrophy of the wall of the left ventricle and conversion of the endocardium into a thick fibroelastic coat, with the capacity of the ventricle sometimes reduced, but often increased.

ICD-10-CM I42.4 is grouped within Diagnostic Related Group(s) (MS-DRG v42.0):

• 314 Other circulatory system diagnoses with mcc
• 315 Other circulatory system diagnoses with cc
• 316 Other circulatory system diagnoses without cc/mcc

Convert I42.4 to ICD-9-CMCode History

• 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
• 2017 (effective 10/1/2016): No change
• 2018 (effective 10/1/2017): No change
• 2019 (effective 10/1/2018): No change
• 2020 (effective 10/1/2019): No change
• 2021 (effective 10/1/2020): No change
• 2022 (effective 10/1/2021): No change
• 2023 (effective 10/1/2022): No change
• 2024 (effective 10/1/2023): No change
• 2025 (effective 10/1/2024): No change

Code annotations containing back-references to I42.4:

• Type 1 Excludes: Q24, I38

Diagnosis Index entries containing back-references to I42.4:

• Anomaly, anomalous (congenital) (unspecified type) Q89.9
  • heartQ24.9
    • fibroelastosis cordis I42.4
• Cardiomyopathy (familial) (idiopathic) I42.9
  • newbornI42.8
    • congenital I42.4
  • congenital I42.4
• Elastomyofibrosis I42.4
• Fibroelastosis I42.4 (cordis) (endocardial) (endomyocardial)
• Newborn (infant) (liveborn) (singleton) Z38.2
  • affected by
    • cardiomyopathyI42.8
      • congenital I42.4
• Sclerosis, sclerotic
  • subendocardial, congenital I42.4