2026 ICD-10-CM Diagnosis Code I51.7Cardiomegaly

ICD-10-CM Codes›I00–I99›I30-I5A›I51

ICD-10-CM I51.7
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I51.7 is a billable ICD-10-CM diagnosis code for cardiomegaly. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) 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

ICD-10-CM Code
I51.7
Billable Status
Yes — Valid for Submission
Code Describes
Cardiomegaly
Short Description
Cardiomegaly
Same as the full description in the CMS dataset.
Parent Code
I51
Complications and ill-defined descriptions of heart disease

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI51Complications and ill-defined descriptions of heart disease
This CodeI51.7Cardiomegaly

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acquired abnormality of right cardiac ventricle
  • Acquired dilatation of left cardiac ventricle
  • Acquired dilatation of right cardiac ventricle
  • Acquired hypertrophy of left cardiac ventricle
  • Acquired hypertrophy of right cardiac ventricle
  • Apex beat displaced
  • Apex beat displaced - LVH
  • Apex beat displaced - RVH
  • Athlete's heart
  • Atrial dilatation
  • Atrial hypertrophy
  • Atrial hypertrophy by EKG
  • Auricular dilatation
  • Bilateral enlargement of atria
  • Cardiac dilatation
  • Cardiac ventricular dilatation
  • Cardiomegaly
  • Congenital dilatation of atrium
  • Cor bovinum
  • EKG: right ventricle hypertrophy
  • Familial idiopathic dilatation of right atrium
  • Giant left atrium
  • Hypertrophic cardiomegaly
  • Left atrial dilatation
  • Left atrial enlargement
  • Left atrial hypertrophy
  • Left atrial hypertrophy by EKG
  • Left cardiac ventricular dilatation
  • Left ventricular hypertrophy
  • Left ventricular hypertrophy by electrocardiogram
  • Markedly enlarged cardiac chamber
  • Mild left ventricular hypertrophy
  • Mildly enlarged cardiac chamber
  • Moderate left ventricular hypertrophy
  • Moderately enlarged cardiac chamber
  • Obstruction of pulmonary great vein due to compression by right atrial dilatation
  • Position of apex beat - finding
  • Right atrial dilatation
  • Right atrial enlargement
  • Right atrial hypertrophy
  • Right atrial hypertrophy by electrocardiogram
  • Right cardiac ventricular dilatation
  • Right ventricular hypertrophy
  • Severe left ventricular hypertrophy
  • Transient ischemic dilatation of left cardiac ventricular cavity
  • Ventricular hypertrophy
  • Ventricular hypertrophy by EKG

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Cardiac dilatation
  • Cardiac hypertrophy
  • Ventricular dilatation

Type 1 Excludes

  • cardiomegaly due to hypertension I11
  • cardiomegaly due to hypertension and chronic kidney disease I13

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Athlete's
      • heart
    • Cardiomegaly
      • idiopathic
    • Hypertrophy, hypertrophic
      • cardiac (chronic) (idiopathic)
    • Preponderance, left or right ventricular

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR015
Other and ill-defined heart disease
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • 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.

  • Cardiomegaly, Exercise-Induced

    non-pathological heart enlargement and other remodeling in cardiac morphology and electrical circuitry found in individuals who participate in intense repeated exercises.

  • Left Ventricular Hypertrophy

    enlargement or overgrowth of the myocardium of the left ventricle, due to chronic pressure overload.

  • Left Ventricular Hypertrophy by ECG Finding|LEFT VENTRICULAR HYPERTROPHY|Left Ventricular Hypertrophy|Left Ventricular Hypertrophy by EKG Finding

    an electrocardiographic finding suggestive of a hypertrophied left ventricle, characterized by large qrs amplitudes and secondary findings of left atrial enlargement, left axis deviation, or typical pattern of st depression and t wave inversion. (cdisc)

  • Left Ventricular Hypertrophy with Strain

    a finding of left ventricular hypertrophy based on the analysis of diagnostic metrics that may indicate a higher risk for cardiovascular events.

  • Left Ventricular Hypertrophy with Strain by ECG Finding|LEFT VENTRICULAR HYPERTROPHY WITH STRAIN|Left Ventricular Hypertrophy With Strain|Left Ventricular Hypertrophy with Strain by EKG Finding

    an electrocardiographic finding suggestive of a hypertrophied left ventricle, characterized by large qrs amplitudes, st depression and t wave inversion. (cdisc)

  • Voltage Criteria Suggesting Left Ventricular Hypertrophy, Without Secondary ECG Findings|VOLTAGE CRITERIA SUGGESTING LEFT VENTRICULAR HYPERTROPHY, WITHOUT SECONDARY ECG FINDINGS

    an electrocardiographic finding of large qrs amplitudes that may indicate left ventricular hypertrophy, but is without any of the secondary findings that are typically seen with this diagnosis: left atrial enlargement, left axis deviation, or typical pattern of st depression and t wave inversion.

  • Right Ventricular Hypertrophy

    enlargement or overgrowth of the myocardium of the right ventricle, due chronic pressure overload.

  • Right Ventricular Hypertrophy by ECG Finding|RIGHT VENTRICULAR HYPERTROPHY|Right Ventricular Hypertrophy by EKG Finding|Right ventricular Hypertrophy

    an electrocardiographic finding suggestive of a hypertrophied right ventricle, characterized by large r wave amplitudes in the right precordial leads and secondary findings of right atrial enlargement, right axis deviation, and typical pattern of st depression and t wave inversion in the right precordial leads. (cdisc)

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 I51.7 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
429.3 Cardiomegaly
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About I51.7Overview

Is I51.7 (Complications and ill-defined descriptions of heart disease) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report cardiomegaly on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does I51.7 group to?

When cardiomegaly is the principal diagnosis on an inpatient stay, it groups to MS-DRG 302, 303, with relative weights from 0.6732 to 1.1966 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I51.7?

Under the General Equivalence Mappings, cardiomegaly converts to ICD-9-CM 429.3 (cardiomegaly). The mapping is a direct match.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.