I51.81 ICD-10-CM Code: Takotsubo syndrome

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for I51.81 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on I51.81 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for I51.81

MedCoder structured workflow — derived from this code’s own official record

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Official instructions as workflow

• Excludes2 — not part of I51.81(1 note)

  Coding workflow: The conditions named in this note are not included in I51.81. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  See the official tabular notes · Guidelines I.A.12.b

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (7)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• 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

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Don’t confuse I51.81 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of I51.81 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• I00— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of heart disease specified as rheumatic adds I00; it is not part of this code and both may be reported when both are documented.

  Full comparison: I51.81 vs I00 →

• I09— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of heart disease specified as rheumatic adds I09; it is not part of this code and both may be reported when both are documented.

  Full comparison: I51.81 vs I09 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name I51.81 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Code First instruction: I5A — Non-ischemic myocardial injury (non-traumatic).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 34 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 3 MS-DRGs: DRG 314 (MDC 05), DRG 315 (MDC 05), DRG 316 (MDC 05).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):CIR015 — Other and ill-defined heart disease (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

I50.33 — Acute on chronic diastolic (congestive) heart failure, I50.40 — Unspecified combined systolic (congestive) and diastolic (congestive) heart failure, I50.41 — Acute combined systolic (congestive) and diastolic (congestive) heart failure, I50.42 — Chronic combined systolic (congestive) and diastolic (congestive) heart failure, I50.43 — Acute on chronic combined systolic (congestive) and diastolic (congestive) heart failure, I50.810 — Right heart failure, unspecified, I50.811 — Acute right heart failure, I50.812 — Chronic right heart failure, I50.813 — Acute on chronic right heart failure, I50.814 — Right heart failure due to left heart failure, I50.82 — Biventricular heart failure, I50.83 — High output heart failure, I50.84 — End stage heart failure, I50.89 — Other heart failure, I50.9 — Heart failure, unspecified, I51.9 — Heart disease, unspecified, I87.8 — Other specified disorders of veins, I87.9 — Disorder of vein, unspecified, I99.8 — Other disorder of circulatory system, I99.9 — Unspecified disorder of circulatory system, +13 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other and ill-defined heart disease).

I25.3 — Aneurysm of heart, I25.41 — Coronary artery aneurysm, 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, I51.5 — Myocardial degeneration, I51.7 — Cardiomegaly, I51.89 — Other ill-defined heart diseases, I51.9 — Heart disease, unspecified, I52 — Other heart disorders in diseases classified elsewhere, I5A — Non-ischemic myocardial injury (non-traumatic), M05.30 — Rheumatoid heart disease with rheumatoid arthritis of unspecified site, M05.311 — Rheumatoid heart disease with rheumatoid arthritis of right shoulder, M05.312 — Rheumatoid heart disease with rheumatoid arthritis of left shoulder, M05.319 — Rheumatoid heart disease with rheumatoid arthritis of unspecified shoulder, M05.321 — Rheumatoid heart disease with rheumatoid arthritis of right elbow, M05.322 — Rheumatoid heart disease with rheumatoid arthritis of left elbow, M05.329 — Rheumatoid heart disease with rheumatoid arthritis of unspecified elbow, M05.331 — Rheumatoid heart disease with rheumatoid arthritis of right wrist, +15 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Dysfunction”, “Cardiomyopathy”; these codes share that main term but sit in a different category of the Tabular List.

I42.2 — Other hypertrophic cardiomyopathy (hypertrophic), I42.4 — Endocardial fibroelastosis (congenital), I42.5 — Other restrictive cardiomyopathy (restrictive NEC), I42.6 — Alcoholic cardiomyopathy (alcoholic), I42.7 — Cardiomyopathy due to drug and external agent (toxic NEC), I42.81 — Arrhythmogenic cardiomyopathy (arrhythmogenic), I42.89 — Other cardiomyopathies not elsewhere classified (newborn), I42.9 — Cardiomyopathy, unspecified, I49.5 — Sick sinus syndrome (sinoatrial node), I50.9 — Heart failure, unspecified (ventricular, with congestive heart failure), J4A.0 — Restrictive allograft syndrome (chronic, lung allograft, mixed), J4A.8 — Other chronic lung allograft dysfunction (chronic, lung allograft, specified NEC), J4A.9 — Chronic lung allograft dysfunction, unspecified (chronic, lung allograft), K31.89 — Other diseases of stomach and duodenum (stomach), K31.9 — Disease of stomach and duodenum, unspecified (pylorus), K59.9 — Functional intestinal disorder, unspecified (colon), K76.89 — Other specified diseases of liver (liver), K82.8 — Other specified diseases of gallbladder (gallbladder), K94.03 — Colostomy malfunction (colostomy), K94.13 — Enterostomy malfunction (ileostomy), +144 more

Contextual Map

Every relationship of I51.81 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run I51.81 with this related code in Claim Check

Hierarchy

• I00-I99 — Chapter 9: Diseases of the Circulatory System (I00-I99) (I00-I99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I30-I5A — Other forms of heart disease[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Code First instructions

• I5A — Non-ischemic myocardial injury (non-traumatic)[Code First]: “takotsubo syndrome (I51.81)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• CIR015 — Other and ill-defined heart disease[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 314 — OTHER CIRCULATORY SYSTEM DIAGNOSES WITH MCC[MS-DRG]: “OTHER CIRCULATORY SYSTEM DIAGNOSES WITH MCC (MDC 05)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 315 — OTHER CIRCULATORY SYSTEM DIAGNOSES WITH CC[MS-DRG]: “OTHER CIRCULATORY SYSTEM DIAGNOSES WITH CC (MDC 05)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 316 — OTHER CIRCULATORY SYSTEM DIAGNOSES WITHOUT CC/MCC[MS-DRG]: “OTHER CIRCULATORY SYSTEM DIAGNOSES WITHOUT CC/MCC (MDC 05)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 05 — Diseases and Disorders of the Circulatory System[MDC crossing]: “Diseases and Disorders of the Circulatory System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 17,209 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Cardiomyopathy (familial) (idiopathic), stress induced[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Cardiomyopathy (familial) (idiopathic), takotsubo[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Dysfunction, left ventricular, following sudden emotional stress[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Dysfunction, ventricular, left, reversible, following sudden emotional stress[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Syndrome, apical ballooning (transient left ventricular)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Syndrome, takotsubo[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Syndrome, transient left ventricular apical ballooning[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (11)

• I51 — Complications and ill-defined descriptions of heart disease[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I51.0 — Cardiac septal defect, acquired[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I51.1 — Rupture of chordae tendineae, not elsewhere classified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I51.2 — Rupture of papillary muscle, not elsewhere classified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I51.3 — Intracardiac thrombosis, not elsewhere classified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I51.4 — Myocarditis, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I51.5 — Myocardial degeneration[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I51.7 — Cardiomegaly[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 3 more

Change history

• FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Coding guidelines Official source data

ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to I51.81 in its code family, with their registry titles.

• 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 diseases
• I51.89 — Other ill-defined heart diseases
• I51.9 — Heart disease, unspecified

View all codes in the I51 family