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A36.81 ICD-10-CM Code: Diphtheritic cardiomyopathy

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 inclusion term
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 85 · RxHCC V08 category 186

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 314 — OTHER CIRCULATORY SYSTEM DIAGNOSES WITH MCC (MDC 05)
  • MS-DRG 315 — OTHER CIRCULATORY SYSTEM DIAGNOSES WITH CC (MDC 05)
  • MS-DRG 316 — OTHER CIRCULATORY SYSTEM DIAGNOSES WITHOUT CC/MCC (MDC 05)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 227 — Cardiomyopathy/Myocarditis

Other models: CMS-HCC V22 HCC 85 · RxHCC V08 HCC 186

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for A36.81 in the official ICD-10-CM tabular list, quoted as published.

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

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Diphtheritic myocarditis

Code Overview

Diphtheritic cardiomyopathy is a billable ICD-10-CM diagnosis code (A36.81).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (3)

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.

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 A36.81 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 2 Excludes1 notes: I41 — Myocarditis in diseases classified elsewhere, I43 — Cardiomyopathy in diseases classified elsewhere.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

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 31 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):CIR005 — Myocarditis and cardiomyopathy (default); INF003 — Bacterial infections.

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.

A52.06 — Other syphilitic heart involvement, B33.20 — Viral carditis, unspecified, B33.21 — Viral endocarditis, B33.22 — Viral myocarditis, I00 — Rheumatic fever without heart involvement, I01.2 — Acute rheumatic myocarditis, I01.8 — Other acute rheumatic heart disease, I01.9 — Acute rheumatic heart disease, unspecified, I09.0 — Rheumatic myocarditis, I09.9 — Rheumatic heart disease, unspecified, I23.0 — Hemopericardium as current complication following acute myocardial infarction, I23.1 — Atrial septal defect as current complication following acute myocardial infarction, I23.2 — Ventricular septal defect as current complication following acute myocardial infarction, I23.3 — Rupture of cardiac wall without hemopericardium as current complication following acute myocardial infarction, I23.6 — Thrombosis of atrium, auricular appendage, and ventricle as current complications following acute myocardial infarction, I23.7 — Postinfarction angina, I23.8 — Other current complications following acute myocardial infarction, I27.841 — Fontan-associated lymphatic dysfunction, I27.848 — Other Fontan-associated condition, I27.849 — Fontan related circulation, unspecified, +10 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Cardiomyopathy/Myocarditis) for risk-adjusted payment.

B33.24 — Viral cardiomyopathy, I42.0 — Dilated cardiomyopathy, I42.1 — Obstructive hypertrophic cardiomyopathy, I42.2 — Other hypertrophic cardiomyopathy, I42.3 — Endomyocardial (eosinophilic) disease, I42.4 — Endocardial fibroelastosis, I42.5 — Other restrictive cardiomyopathy, I42.6 — Alcoholic cardiomyopathy, I42.8 — Other cardiomyopathies, I42.9 — Cardiomyopathy, unspecified, I43 — Cardiomyopathy in diseases classified elsewhere, I51.4 — Myocarditis, unspecified, I51.5 — Myocardial degeneration

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Heart Failure with Heart Assist Device/Artificial Heart, Acute on Chronic Heart Failure, Acute Heart Failure (Excludes Acute on Chronic), Heart Failure, Except End-Stage and Acute

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Myocarditis and cardiomyopathy, Bacterial infections).

A38.1 — Scarlet fever with myocarditis, A39.50 — Meningococcal carditis, unspecified, A39.52 — Meningococcal myocarditis, B26.82 — Mumps myocarditis, B33.20 — Viral carditis, unspecified, B33.22 — Viral myocarditis, B33.24 — Viral cardiomyopathy, B58.81 — Toxoplasma myocarditis, D86.85 — Sarcoid myocarditis, I01.2 — Acute rheumatic myocarditis, I09.0 — Rheumatic myocarditis, I25.5 — Ischemic cardiomyopathy, I40.0 — Infective myocarditis, I40.1 — Isolated myocarditis, I40.8 — Other acute myocarditis, I40.9 — Acute myocarditis, unspecified, I41 — Myocarditis in diseases classified elsewhere, I42.0 — Dilated cardiomyopathy, I42.1 — Obstructive hypertrophic cardiomyopathy, I42.2 — Other hypertrophic cardiomyopathy, +408 more

Same Index main term, other category

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

A01.02 — Typhoid fever with heart involvement (typhoid), A18.84 — Tuberculosis of heart (tuberculous), A38.1 — Scarlet fever with myocarditis (in, scarlet fever), A39.52 — Meningococcal myocarditis (meningococcal), A52.06 — Other syphilitic heart involvement (syphilitic), A54.83 — Gonococcal heart infection (gonococcal), A69.29 — Other conditions associated with Lyme disease (in, Lyme disease), A75.0 — Epidemic louse-borne typhus fever due to Rickettsia prowazekii (in, epidemic louse-borne typhus), A75.9 — Typhus fever, unspecified (in, typhus NEC), B26.82 — Mumps myocarditis (mumps), B33.22 — Viral myocarditis (Coxsackie), B58.81 — Toxoplasma myocarditis (in, toxoplasmosis), D86.85 — Sarcoid myocarditis (in, sarcoidosis), I01.2 — Acute rheumatic myocarditis (active, rheumatic), I02.0 — Rheumatic chorea with heart involvement (active, rheumatic, with chorea), I09.0 — Rheumatic myocarditis (rheumatic), I40.0 — Infective myocarditis (septic), I40.1 — Isolated myocarditis (isolated), I40.8 — Other acute myocarditis (toxic), I40.9 — Acute myocarditis, unspecified (active), +2 more

Contextual Map

Every relationship of A36.81 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 A36.81 with these 2 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 227 — Cardiomyopathy/Myocarditis [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

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

  • Diphtheria, diphtheritic (gangrenous) (hemorrhagic), myocarditis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Myocarditis (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile), diphtheritic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Myocarditis (with arteriosclerosis)(chronic)(fibroid) (interstitial) (old) (progressive) (senile), in (due to), diphtheria[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (13)

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
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
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release 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

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "A36.81 — Diphtheritic cardiomyopathy." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/a36.81-diphtheritic-cardiomyopathy

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Diphtheritic cardiomyopathy

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to A36.81 in its code family, with their registry titles.

View all codes in the A36 family