Complications and ill-defined descriptions of heart disease (I51) ICD-10-CM
The I51 code range covers complications and ill-defined descriptions of heart disease with 12 ICD-10-CM diagnosis codes. 10 of them are billable and valid for claim submission in fiscal year 2027, and the category headers group them but cannot themselves be billed.
Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
Codes in the I51 Range 12 codes · 10 billable
- I51 Complications and ill-defined descriptions of heart diseaseNon-billable
- I51.0 Cardiac septal defect, acquired
- I51.1 Rupture of chordae tendineae, not elsewhere classified
- I51.2 Rupture of papillary muscle, not elsewhere classified
- I51.3 Intracardiac thrombosis, not elsewhere classified
- I51.4 Myocarditis, unspecified
- I51.5 Myocardial degeneration
- I51.7 Cardiomegaly
- I51.8 Other ill-defined heart diseasesNon-billable
- I51.81 Takotsubo syndrome
- I51.89 Other ill-defined heart diseases
- I51.9 Heart disease, unspecified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the I51 range.
Cardiomegaly
Enlargement of the HEART, usually indicated by a cardiothoracic ratio above 0.50. Heart enlargement may involve the right, the left, or both HEART VENTRICLES or HEART ATRIA. Cardiomegaly is a nonspecific symptom seen in patients with chronic systolic heart failure (HEART FAILURE) or several forms of CARDIOMYOPATHIES.
Heart Diseases
Pathological conditions involving the HEART including its structural and functional abnormalities.
Heart Septal Defects
Abnormalities in any part of the HEART SEPTUM resulting in abnormal communication between the left and the right chambers of the heart. The abnormal blood flow inside the heart may be caused by defects in the ATRIAL SEPTUM, the VENTRICULAR SEPTUM, or both.
Myocardial Degeneration
Degeneration of myocardial tissue.
Myocarditis
Inflammatory processes of the muscular walls of the heart (MYOCARDIUM) which result in injury to the cardiac muscle cells (MYOCYTES, CARDIAC). Manifestations range from subclinical to sudden death (DEATH, SUDDEN). Myocarditis in association with cardiac dysfunction is classified as inflammatory CARDIOMYOPATHY usually caused by INFECTION, autoimmune diseases, or responses to toxic substances. Myocarditis is also a common cause of DILATED CARDIOMYOPATHY and other cardiomyopathies.
Takotsubo Cardiomyopathy
A transient left ventricular apical dysfunction or ballooning accompanied by electrocardiographic (ECG) T wave inversions. This abnormality is associated with high levels of CATECHOLAMINES, either administered or endogenously secreted from a tumor or during extreme stress.
About the I51 Code Range
These codes describe specific heart abnormalities and heart disease recorded in less precise terms.
The subdivisions distinguish an acquired defect in the heart's dividing wall (I51.0), ruptures of named heart structures (I51.1 and I51.2), and a blood clot inside the heart (I51.3). They also distinguish heart muscle inflammation (I51.4), heart muscle degeneration (I51.5), and an enlarged heart (I51.7).
I51.8 divides into Takotsubo syndrome (I51.81) and other ill-defined heart diseases (I51.89). I51.9 describes heart disease without a specified type.
Questions About This Page
How many billable codes are in the I51 range?
Of the 12 codes in this range, 10 are billable and valid for claim submission from October 1, 2026 through September 30, 2027. Category header codes group them but cannot be reported on claims.
What does the I51 range classify?
The range classifies complications and ill-defined descriptions of heart disease. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
