2026 ICD-10-CM Diagnosis Code I51.81Takotsubo syndrome

ICD-10-CM Codes›I00–I99›I30-I5A›I51

ICD-10-CM I51.81
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

I51.81 is a billable ICD-10-CM diagnosis code for takotsubo syndrome. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 314 through 316. Coders also document this condition as takotsubo cardiomyopathy. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other and ill-defined heart disease.

Code Identity

ICD-10-CM Code
I51.81
Billable Status
Yes — Valid for Submission
Code Describes
Takotsubo syndrome
Short Description
Takotsubo syndrome
Same as the full description in the CMS dataset.
Parent Code
I51.8
Other ill-defined heart diseases

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI30-I5AOther forms of heart disease
CategoryI51Complications and ill-defined descriptions of heart disease
This CodeI51.81Takotsubo syndrome

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Takotsubo cardiomyopathy

Tabular List NotesGuidance

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

Inclusion Terms

  • Reversible left ventricular dysfunction following sudden emotional stress
  • Stress induced cardiomyopathy
  • Takotsubo cardiomyopathy
  • Transient left ventricular apical ballooning syndrome

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.

    • Cardiomyopathy(familial) (idiopathic)
      • stress induced
    • Cardiomyopathy(familial) (idiopathic)
      • takotsubo
    • Dysfunction
      • left ventricular, following sudden emotional stress
    • Dysfunction
      • ventricular
        • left, reversible, following sudden emotional stress
    • Syndrome
      • apical ballooning (transient left ventricular)
    • Syndrome
      • takotsubo
    • Syndrome
      • transient left ventricular apical ballooning

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

  • 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.

Patient EducationClinical

Cardiomyopathy

Cardiomyopathy is the name for diseases of the heart muscle. These diseases enlarge your heart muscle or make it thicker and more rigid than normal. In rare cases, scar tissue replaces the muscle tissue.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert I51.81 to ICD-9-CMHistory

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

ICD-9-CM
429.83 Takotsubo syndrome
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 I51.81Overview

Is I51.81 (Other ill-defined heart diseases) a billable code?

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

What MS-DRG does I51.81 group to?

When takotsubo syndrome is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 315, 316, with relative weights from 0.6821 to 2.0852 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of I51.81?

Under the General Equivalence Mappings, takotsubo syndrome converts to ICD-9-CM 429.83 (takotsubo syndrome). 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.