2019 ICD-10-CM Diagnosis Code I42.1

Obstructive hypertrophic cardiomyopathy

    2016 2017 2018 2019 Billable/Specific Code
  • I42.1 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2019 edition of ICD-10-CM I42.1 became effective on October 1, 2018.
  • This is the American ICD-10-CM version of I42.1 - other international versions of ICD-10 I42.1 may differ.
Applicable To
  • Hypertrophic subaortic stenosis (idiopathic)
The following code(s) above I42.1 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to I42.1:
  • I00-I99
    2019 ICD-10-CM Range I00-I99

    Diseases of the circulatory system

    Type 2 Excludes
    • certain conditions originating in the perinatal period (P04-P96)
    • certain infectious and parasitic diseases (A00-B99)
    • complications of pregnancy, childbirth and the puerperium (O00-O9A)
    • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
    • endocrine, nutritional and metabolic diseases (E00-E88)
    • injury, poisoning and certain other consequences of external causes (S00-T88)
    • neoplasms (C00-D49)
    • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
    • systemic connective tissue disorders (M30-M36)
    • transient cerebral ischemic attacks and related syndromes (G45.-)
    Diseases of the circulatory system
  • I42
    ICD-10-CM Diagnosis Code I42

    Cardiomyopathy

      2016 2017 2018 2019 Non-Billable/Non-Specific Code
    Code First
    • pre-existing cardiomyopathy complicating pregnancy and puerperium (O99.4)
    Includes
    • myocardiopathy
    Type 2 Excludes
    • ischemic cardiomyopathy (I25.5)
    • peripartum cardiomyopathy (O90.3)
    • ventricular hypertrophy (I51.7)
    Cardiomyopathy
Approximate Synonyms
  • Cardiomyopathy, hypertrophic obstructive
  • Hypertrophic obstructive cardiomyopathy
  • Idiopathic hypertrophic subaortic stenosis
Clinical Information
  • 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.
  • A form of cardiac muscle disease, characterized by left and/or right ventricular hypertrophy (hypertrophy, left ventricular; hypertrophy, right ventricular), frequent asymmetrical involvement of the heart septum, and normal or reduced left ventricular volume. Risk factors include hypertension; aortic stenosis; and gene mutation; (familial hypertrophic cardiomyopathy).
  • Myocardial disease characterized by hypertrophy, involving mainly the interventricular septum, interfering with left ventricular emptying.
ICD-10-CM I42.1 is grouped within Diagnostic Related Group(s) (MS-DRG v36.0):
  • 314 Other circulatory system diagnoses with mcc
  • 315 Other circulatory system diagnoses with cc
  • 316 Other circulatory system diagnoses without cc/mcc

Convert I42.1 to ICD-9-CM

Code 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
Code annotations containing back-references to I42.1:
  • Type 1 Excludes: I35
    ICD-10-CM Diagnosis Code I35

    Nonrheumatic aortic valve disorders

      2016 2017 2018 2019 Non-Billable/Non-Specific Code
    Type 1 Excludes
    • aortic valve disorder of unspecified cause but with diseases of mitral and/or tricuspid valve(s) (I08.-)
    • aortic valve disorder specified as congenital (Q23.0, Q23.1)
    • aortic valve disorder specified as rheumatic (I06.-)
    • hypertrophic subaortic stenosis (I42.1)

Diagnosis Index entries containing back-references to I42.1:
  • Cardiomyopathy (familial) (idiopathic) I42.9
    ICD-10-CM Diagnosis Code I42.9

    Cardiomyopathy, unspecified

      2016 2017 2018 2019 Billable/Specific Code
    Applicable To
    • Cardiomyopathy (primary) (secondary) NOS
    • hypertrophic (nonobstructive) I42.2
      ICD-10-CM Diagnosis Code I42.2

      Other hypertrophic cardiomyopathy

        2016 2017 2018 2019 Billable/Specific Code
      Applicable To
      • Nonobstructive hypertrophic cardiomyopathy
  • Myocardiopathy (congestive) (constrictive) (familial) (hypertrophic nonobstructive) (idiopathic) (infiltrative) (obstructive) (primary) (restrictive) (sporadic) I42.9
    - see also Cardiomyopathy
    ICD-10-CM Diagnosis Code I42.9

    Cardiomyopathy, unspecified

      2016 2017 2018 2019 Billable/Specific Code
    Applicable To
    • Cardiomyopathy (primary) (secondary) NOS
    • hypertrophic obstructive I42.1
  • Stenosis, stenotic (cicatricial) - see also Stricture
    • myocardium, myocardial - see also Degeneration, myocardial
      • hypertrophic subaortic I42.1 (idiopathic)
    • subaortic (congenital) Q24.4
      ICD-10-CM Diagnosis Code Q24.4

      Congenital subaortic stenosis

        2016 2017 2018 2019 Billable/Specific Code POA Exempt
      • hypertrophic I42.1 (idiopathic)
    • hypertrophic subaortic I42.1 (idiopathic)
  • Stricture - see also Stenosis
    • myocardium, myocardial I51.5
      ICD-10-CM Diagnosis Code I51.5

      Myocardial degeneration

        2016 2017 2018 2019 Billable/Specific Code
      Applicable To
      • Fatty degeneration of heart or myocardium
      • Myocardial disease
      • Senile degeneration of heart or myocardium
      • hypertrophic subaortic I42.1 (idiopathic)
    • subaortic Q24.4
      ICD-10-CM Diagnosis Code Q24.4

      Congenital subaortic stenosis

        2016 2017 2018 2019 Billable/Specific Code POA Exempt
      • hypertrophic I42.1 (acquired) (idiopathic)

ICD-10-CM Codes Adjacent To I42.1
I38 Endocarditis, valve unspecified
I39 Endocarditis and heart valve disorders in diseases classified elsewhere
I40 Acute myocarditis
I40.0 Infective myocarditis
I40.1 Isolated myocarditis
I40.8 Other acute myocarditis
I40.9 Acute myocarditis, unspecified
I41 Myocarditis in diseases classified elsewhere
I42 Cardiomyopathy
I42.0 Dilated cardiomyopathy
I42.1 Obstructive hypertrophic cardiomyopathy
I42.2 Other hypertrophic cardiomyopathy
I42.3 Endomyocardial (eosinophilic) disease
I42.4 Endocardial fibroelastosis
I42.5 Other restrictive cardiomyopathy
I42.6 Alcoholic cardiomyopathy
I42.7 Cardiomyopathy due to drug and external agent
I42.8 Other cardiomyopathies
I42.9 Cardiomyopathy, unspecified
I43 Cardiomyopathy in diseases classified elsewhere
I44 Atrioventricular and left bundle-branch block

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.