I51.89 Other ill-defined heart diseases

The ICD-10-CM code for Other ill-defined heart diseases is I51.89 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

9: Diseases of the circulatory system (I00-I99)

Section

I30-I5A: Other forms of heart disease (I30-I5A)

Category I51

12 codes (10 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to I51.89:

• Carditis (acute) (bacterial) (chronic) (subacute)
• Pancarditis (acute) (chronic)
• Hyperkinesia, hyperkinetic (disease) (reaction) (syndrome) (childhood) (adolescence) › heart
• Dysfunction › heart
• Disorder (of) › cardiac, functional
• Dysfunction › papillary muscle
• Asynergia, asynergy › ventricular
• Hemorrhage, hemorrhagic (concealed) › heart

Inclusion Terms

• Carditis (acute)(chronic)
• Pancarditis (acute)(chronic)

U.S. Hospital Utilization

• An estimated 8,195 U.S. inpatient stays in 2023 included I51.89 among the documented diagnoses.
• 180 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

I11 + addl code for I50/I51 heart conditions (incl I50.-, I51.4, I51.89, I51.9)

1) Hypertension with Heart Disease Hypertension with heart conditions classified to I50.-, Heart failure, I51.4, Myocarditis, unspecified, I51.89, Other ill-defined heart diseases, and I51.9, Heart disease, unspecified, is assigned to a code from category I11, Hypertensive heart disease. Use additional code(s) from category I50, Heart failure, or I51, Complications and ill-defined descriptions of heart disease, to identify the heart condition.

Code separately if documented unrelated; assign I10 or I15; sequence per encounter

The same heart conditions (I50.-, I51.4-I51.7, I51.89, I51.9) with hypertension are coded separately if the provider has documented they are unrelated to the hypertension. The applicable hypertension code I10, Essential (primary) hypertension, or a code from category I15, Secondary hypertension, should be assigned. Sequence according to the circumstances of the admission/encounter.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)