2027 ICD-10-CM Diagnosis Code I51.9Heart disease, unspecified
ICD-10-CM Codes›I00–I99›I30-I5A›I51
- Billable — Valid for Submission
- Chronic Condition
I51.9 is a billable ICD-10-CM diagnosis code for heart disease, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 302 through 303. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other and ill-defined heart disease.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acute heart disease
- Cachexia
- Cardiac cachexia
- Cardiac cirrhosis
- Cardiac complication
- Cardiac disease in pregnancy
- Cardiac disease treatment started
- Cardiac portal cirrhosis
- Cardiac treatment changed
- Cardiac: dubious diagnostic criteria
- Chronic heart disease
- Disorder of left atrium as complication of procedure
- Disorder of right cardiac ventricle
- Distribution of body fat loss - finding
- Heart disease
- Heart disease caused by ionizing radiation
- Heart disease co-occurrent with human immunodeficiency virus infection
- Heart disease in mother complicating childbirth
- Heart disease in mother complicating pregnancy, childbirth AND/OR puerperium
- Hepatic congestion
- Hypogonadism with anosmia
- Hypogonadotropic hypogonadism due to isolated gonadotropin deficiency
- Kallman syndrome with heart disease
- Loss of sense of smell
- Myocardial lesion
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to I51.9: its own notes plus those printed at I51 and Chapter 9. A note printed at a category, block or chapter applies to every code under it.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may 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.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Cardiopathy See Also: Disease, heart; I51.9
Disease, diseased See Also: Syndrome;
heart (organic) I51.9
cryptogenic I51.9
ventricular I51.9
cardiac See Also: Disease, heart; I51.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Heart Diseases
pathological conditions involving the heart including its structural and functional abnormalities.
Patient EducationClinical
Heart Diseases
Heart disease is a general term that includes many types of heart problems. It's a type of cardiovascular disease, which means heart and blood vessel disease.
The full article covers:
- What is heart disease?
- What are the types of heart disease?
- What causes heart diseases?
- Who is more likely to develop heart diseases?
- What are the symptoms of heart disease?
- How are heart diseases diagnosed?
- What are the treatments for heart disease?
- Can heart diseases be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I51.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I51.9Overview
What is the ICD-10 code for heart disease, unspecified?
The ICD-10-CM code for heart disease, unspecified is I51.9 (sometimes written as I519). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is I51.9 (Complications and ill-defined descriptions of heart disease) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report heart disease, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does I51.9 group to?
When heart disease, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 302, 303, with relative weights from 0.6610 to 1.1993 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of I51.9?
Under the General Equivalence Mappings, heart disease, unspecified converts to ICD-9-CM 429.9 (heart disease NOS). The mapping is approximate, so confirm the match fits the documentation.
