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I42.1 ICD-10-CA code: Obstructive hypertrophic cardiomyopathy

I42.1 is the ICD-10-CA code for “Obstructive hypertrophic cardiomyopathy” in CIHI’s FY 2026–2027 release, in effect from Apr 1, 2026.

Official description

I42.1

Obstructive hypertrophic cardiomyopathy

ICD-10-CA · Canada · Also written I421

Index terms

Entries in CIHI’s alphabetical index that lead to I42.1. Searching the index by the condition the note names is how coders reach this code.

  • Stenosis (cicatricial), subaortic (congenital), hypertrophic
  • Cardiomyopathy (familial) (idiopathic), hypertrophic (nonobstructive), obstructive

Notes for I42.1

As CIHI prints them, with any note I42.1 takes from the headings above it.

Includes

  • Hypertrophic subaortic stenosis

Excludes

Conditions classified elsewhere.

  • Cardiomyopathy complicating:• pregnancy (O99.4)• puerperium (O90.3)ischaemic cardiomyopathy (I25.5)From I42 Cardiomyopathy
  • Certain:• conditions originating in the perinatal period (P00-P96)• infectious and parasitic diseases (A00-B99)complications of pregnancy, childbirth and the puerperium (O00-O99)congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)endocrine, nutritional and metabolic diseases (E00-E90)injury, poisoning and certain other consequences of external causes (S00-T98)neoplasms (C00-D48)symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)systemic connective tissue disorders (M30-M36)transient cerebral ischaemic attacks and related syndromes (G45.-)From Chapter 9: Diseases of the circulatory system (I00-I99)

Where I42.1 sits

  1. 1ChapterChapter 9: Diseases of the circulatory system (I00-I99)
  2. 2Block I30-I52Other forms of heart disease
  3. 3Category I42Cardiomyopathy
  4. 4Valid code I42.1Obstructive hypertrophic cardiomyopathy

Source and release

Data release
ICD-10-CA · FY 2026–2027
Effective date
Apr 1, 2026
Publisher
CIHI

This page is built from the ICD-10-CA catalog that Vero Codes reads when it suggests codes: Canadian Institute for Health Information’s FY 2026–2027 release, imported from the publisher’s file and checked against it. The description, notes and structured data come from the same record.

See I42.1 in the CIHI source

Frequently asked questions

What does ICD-10-CA code I42.1 mean?

I42.1 is the ICD-10-CA code for “Obstructive hypertrophic cardiomyopathy” in CIHI’s ICD-10-CA FY 2026–2027 release.

Where is I42.1 in ICD-10-CA?

I42.1 sits under I42 Cardiomyopathy, within I30-I52 Other forms of heart disease, within Chapter 9: Diseases of the circulatory system (I00-I99).

What coding notes apply to I42.1?

ICD-10-CA lists Includes, Excludes notes for I42.1, including those from the headings it sits under. They are listed on this page with where each one comes from.

Which ICD-10-CA release does this page use?

It uses CIHI’s FY 2026–2027 release, in effect from Apr 1, 2026 to Mar 31, 2027. It is a reference: confirm the code against the current list and the payer’s rules before you submit it.

Codes beside I42.1

I42.0Dilated cardiomyopathyI42.2Other hypertrophic cardiomyopathyI42.3Endomyocardial (eosinophilic) diseaseI42.4Endocardial fibroelastosisI42.5Other restrictive cardiomyopathyI42.6Alcoholic cardiomyopathyI42.7Cardiomyopathy due to drugs and other external agentsI42.8Other cardiomyopathiesI42.9Cardiomyopathy, unspecified