I42.1 — Obstructive hypertrophic cardiomyopathy

BillableCC

Is I42.1 billable?

Yes — I42.1 is billable for FY2027. I42.1 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. I42.1 may be submitted for encounters from October 1, 2026 through September 30, 2027.

I42.1 at a glance

Code	I42.1
Description	Obstructive hypertrophic cardiomyopathy
Billable	Yes
Code set	ICD-10-CM FY2027
Valid for encounters	October 1, 2026 – September 30, 2027

Which MS-DRGs does I42.1 group to?

I42.1 sits in MDC 05 and helps define the logic of 3 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.

314Other Circulatory System Diagnoses with MCCmedical
315Other Circulatory System Diagnoses with CCmedical
316Other Circulatory System Diagnoses without CC/MCCmedical

As a secondary diagnosis, I42.1 is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG.

How is I42.1 listed in the Alphabetic Index?

These are the routes through the Alphabetic Index that lead to I42.1. They show the wording a clinician may have documented, which often differs from the Tabular description.

Myocardiopathy › hypertrophic obstructive (congestive) (constrictive) (familial) (hypertrophic nonobstructive) (idiopathic) (infiltrative) (obstructive) (primary) (restrictive) (sporadic)
Stenosis, stenotic › hypertrophic subaortic (cicatricial)
Cardiomyopathy › hypertrophic › obstructive (familial) (idiopathic)
Stenosis, stenotic › myocardium, myocardial › hypertrophic subaortic (cicatricial)
Stenosis, stenotic › subaortic › hypertrophic (cicatricial)
Stricture › myocardium, myocardial › hypertrophic subaortic
Stricture › subaortic › hypertrophic

Inclusion terms

Alternative wording in documentation that is classified to I42.1.

Hypertrophic subaortic stenosis (idiopathic)

Code first — inherited from I42

The underlying condition below must be sequenced before I42.1. I42.1 describes a manifestation and cannot be the principal or first-listed diagnosis.

pre-existing cardiomyopathy complicating pregnancy and puerperium (O99.4)

Excludes2 — not included here — inherited from Chapter 9

The conditions below are not part of I42.1, but a patient may have both at the same time. When documentation supports it, I42.1 and the excluded code may both be reported.

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.-)

Excludes2 — not included here — inherited from I42

The conditions below are not part of I42.1, but a patient may have both at the same time. When documentation supports it, I42.1 and the excluded code may both be reported.

ischemic cardiomyopathy (I25.5)
peripartum cardiomyopathy (O90.3)
ventricular hypertrophy (I51.7)

How long has I42.1 existed?

I42.1 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.

Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.