ICD10BillableValid for clinical use
ICD-10 Code I51.9: Heart disease, unspecified
Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026
What is this code?
ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the circulatory system (I00-I99).
When is it used?
- May be used when a clinician documents heart disease, unspecified in a patient's medical record.
- May appear in hospital records, claims, referrals, and clinical documentation.
- This code can be used as a clinically usable diagnosis entry in standardized coding workflows.
What it does not mean
- A code alone does not explain severity, treatment plan, or outcome.
- A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
Code hierarchy
chapter
9Diseases of the circulatory system (I00-I99)
block
I30-I5AOther forms of heart disease
category
I51Complications and ill-defined descriptions of heart disease
currentI51
Where you may see this code
You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.
Related specialists
CardiologistGeneral PhysicianENT Specialist
Related codes
I51.0Cardiac septal defect, acquiredcodeI51.1Rupture of chordae tendineae, not elsewhere classifiedcodeI51.2Rupture of papillary muscle, not elsewhere classifiedcodeI51.3Intracardiac thrombosis, not elsewhere classifiedcodeI51.4Myocarditis, unspecifiedcodeI51.5Myocardial degenerationcodeI51.7CardiomegalycodeI51.8Other ill-defined heart diseasescategory
Sibling codes
I51.0Cardiac septal defect, acquiredbillableI51.1Rupture of chordae tendineae, not elsewhere classifiedbillableI51.2Rupture of papillary muscle, not elsewhere classifiedbillableI51.3Intracardiac thrombosis, not elsewhere classifiedbillableI51.4Myocarditis, unspecifiedbillableI51.5Myocardial degenerationbillableI51.7CardiomegalybillableI51.8Other ill-defined heart diseases
Coverage-related procedures and services
CPT 82172high
APOLIPOPROTEIN, EACH
Source: CMS coverage guidance
CPT 86141high
C-REACTIVE PROTEIN; HIGH SENSITIVITY (HSCRP)
Source: CMS coverage guidance
CPT 83090high
HOMOCYSTEINE
Source: CMS coverage guidance
CPT 83695high
LIPOPROTEIN (A)
Source: CMS coverage guidance
CPT 83700high
LIPOPROTEIN, BLOOD; ELECTROPHORETIC SEPARATION AND QUANTITATION
Source: CMS coverage guidance
CPT 83701high
LIPOPROTEIN, BLOOD; HIGH RESOLUTION FRACTIONATION AND QUANTITATION OF LIPOPROTEINS INCLUDING LIPOPROTEIN SUBCLASSES WHEN PERFORMED (EG, ELECTROPHORESIS, ULTRACENTRIFUGATION)
Source: CMS coverage guidance
Mapped diagnoses and classifications
SNOMED_CT 111970001high
Abnormal cardiovascular function
Source: SNOMED International ICD-10 map
SNOMED_CT 127337006high
Acute heart disease
Source: SNOMED International ICD-10 map
SNOMED_CT 284529003high
Cardiac cachexia
Source: SNOMED International ICD-10 map
SNOMED_CT 40172005high
Cardiac complication
Source: SNOMED International ICD-10 map
SNOMED_CT 362999008high
Cardiac complication of procedure
Source: SNOMED International ICD-10 map
SNOMED_CT 128238001high
Chronic heart disease
Source: SNOMED International ICD-10 map
Coding guidelines
Compatibility
Legacy and official ICD code match exactly.
Legacy codes
I51.9
Common synonyms
Heart disease, unspecifiedHeart disease
Frequently asked questions
About this content
This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.