ICD-10-CM 2027 diagnosis code

I51Complications and ill-defined descriptions of heart disease

Not billable — use a more specific code

I51 is a header code, so it can't be reported by itself. Choose one of the 9 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About I51

I51 is the ICD-10-CM diagnosis code for complications and ill-defined descriptions of heart disease. It belongs to block I30-I5A (other forms of heart disease) and chapter 9 (diseases of the circulatory system). It is a header code, so it can't be reported by itself; one of its 9 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: I51.0 (acquired), I51.1 (classified), I51.2 (classified), I51.3 (classified), I51.4 (unspecified), I51.5 (degeneration), I51.7 (Cardiomegaly), I51.8 (diseases) and 1 more.

The conditions in its Excludes2 note aren't part of I51, but may be coded alongside it if the patient has both: heart disease specified as rheumatic (I00-I09).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under I51

Coding notes

Excludes2Not included here — may be reported together if both conditions exist

heart disease specified as rheumatic (I00-I09)

Notes that apply from higher levels

Instructions written at a parent level also apply to I51.

Broader instructions also apply from Chapter 9: Diseases of the circulatory system.

Code history

2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about I51

Is I51 billable?: No. I51 is a header code. Report one of its more specific subcodes instead.