I51.8 – Other ill-defined heart diseases

ICD-10-CM 2027 diagnosis code · Other forms of heart disease

Non-billable header

ICD-10-CM code I51.8

Code: I51.8 (claims format: I518)
Description: Other ill-defined heart diseases
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 9. Diseases of the circulatory system (I00-I99)
Block: I30-I5A Other forms of heart disease
Parent codes: I51

Billable codes under I51.8

I51.8 is a header code and cannot be used on claims. Choose the most specific code:

I51.81 – Takotsubo syndromeBillable
I51.89 – Other ill-defined heart diseasesBillable

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

I51 – Complications and ill-defined descriptions of heart disease

Excludes2 (not included here):

heart disease specified as rheumatic (I00-I09)

Related codes in I51

I51.0 – Cardiac septal defect, acquiredBillable
I51.1 – Rupture of chordae tendineae, not elsewhere classifiedBillable
I51.2 – Rupture of papillary muscle, not elsewhere classifiedBillable
I51.3 – Intracardiac thrombosis, not elsewhere classifiedBillable
I51.4 – Myocarditis, unspecifiedBillable
I51.5 – Myocardial degenerationBillable
I51.7 – CardiomegalyBillable
I51.9 – Heart disease, unspecifiedBillable

Frequently asked questions

What is ICD-10 code I51.8?

I51.8 is the ICD-10-CM code for other ill-defined heart diseases, in the block I30-I5A (Other forms of heart disease).

Is I51.8 a billable code?

No. I51.8 is a header code with more specific child codes; report one of the billable codes listed above.

What category does I51.8 belong to?

It belongs to category I51 – Complications and ill-defined descriptions of heart disease.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.