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I33.0 ICD-10-CM Code: Acute and subacute infective endocarditis

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

Coding at a Glance

Tabular directives
8 inclusion terms · 2 Excludes1 · 1 use-additional code

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 v44, Appendix B.

  • MS-DRG 288 — ACUTE AND SUBACUTE ENDOCARDITIS WITH MCC (MDC 05)
  • MS-DRG 289 — ACUTE AND SUBACUTE ENDOCARDITIS WITH CC (MDC 05)
  • MS-DRG 290 — ACUTE AND SUBACUTE ENDOCARDITIS WITHOUT CC/MCC (MDC 05)
  • MS-DRG 791 — PREMATURITY WITH MAJOR PROBLEMS (MDC 15)
  • MS-DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)
  • MS-DRG 974 — HIV WITH MAJOR RELATED CONDITION WITH MCC (MDC 25)
  • MS-DRG 975 — HIV WITH MAJOR RELATED CONDITION WITH CC (MDC 25)
  • MS-DRG 976 — HIV WITH MAJOR RELATED CONDITION WITHOUT CC/MCC (MDC 25)

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.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for I33.0 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on I33.0 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Bacterial endocarditis (acute) (subacute)
  • Infective endocarditis (acute) (subacute) NOS
  • Endocarditis lenta (acute) (subacute)
  • Malignant endocarditis (acute) (subacute)
  • Purulent endocarditis (acute) (subacute)
  • Septic endocarditis (acute) (subacute)
  • Ulcerative endocarditis (acute) (subacute)
  • Vegetative endocarditis (acute) (subacute)

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Source: inherited from I33

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code (B95-B97) to identify infectious agent

Coder workflow for I33.0

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

Before you code I33.0

  1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with I33.0. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support a condition named in I33.0’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewI01.1, I38

Consider I33.0. Then work the Use Additional Code note, and confirm the code is valid for the date of service in the Verify section.

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).
Acuity
Acute or chronic as documented; when both are documented and separate codes exist, both are reported with the acute code first (Guidelines I.B.8).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

  • Excludes1 — check before selecting I33.0(2 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with I33.0: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareI01.1, I38

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

  • Use Additional Code — after identifying I33.0(1 note)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with I33.0 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: Both the condition I33.0 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewI01.1, I38

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with I33.0?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

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.

Don’t confuse I33.0 with…

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

The codes most likely to be picked instead of I33.0 — 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.

  • I01.1— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of acute rheumatic endocarditis moves the case to I01.1; the two are not reported together unless documented as unrelated.

    Full comparison: I33.0 vs I01.1 →

  • I38— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of endocarditis NOS moves the case to I38; the two are not reported together unless documented as unrelated.

    Full comparison: I33.0 vs I38 →

  • I33.9— Specificity relationship (Review)

    Overlapping diagnoses in the same category.

    Overlapping codes in the same category — the documentation decides which is the more specific fit.

    What moves you there: A record that documents no more than “Acute and subacute endocarditis, unspecified” takes I33.9; specificity in the record moves it back here.

    Full comparison: I33.0 vs I33.9 →

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.

Code Overview

Acute and subacute infective endocarditis is a billable ICD-10-CM diagnosis code (I33.0).

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 (31)

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

  • MCC as a secondary diagnosis (FY2027). 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 I33.0 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 Code First instructions across 2 chapters: I76 — Septic arterial embolism, M02 — Postinfective and reactive arthropathies.

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 (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: MCC — Major 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 15 clinically related codes on its CMS exclusion list. Does not count toward severity when the stay groups to DRGs 974-976 (HIV with Major Related Condition).

Named in the grouper logic of 8 MS-DRGs: DRG 288 (MDC 05), DRG 289 (MDC 05), DRG 290 (MDC 05), DRG 791 (MDC 15), DRG 793 (MDC 15), DRG 974 (MDC 25), DRG 975 (MDC 25), DRG 976 (MDC 25).

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

Clinical classification (AHRQ CCSR):CIR004 — Endocarditis and endocardial 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 MCC — 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.

I01.1 — Acute rheumatic endocarditis, I08.1 — Rheumatic disorders of both mitral and tricuspid valves, I08.2 — Rheumatic disorders of both aortic and tricuspid valves, I08.3 — Combined rheumatic disorders of mitral, aortic and tricuspid valves, I09.1 — Rheumatic diseases of endocardium, valve unspecified, I27.841 — Fontan-associated lymphatic dysfunction, I27.848 — Other Fontan-associated condition, I27.849 — Fontan related circulation, unspecified, I33.9 — Acute and subacute endocarditis, unspecified, I38 — Endocarditis, valve 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

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Endocarditis and endocardial disease).

A18.84 — Tuberculosis of heart, A32.82 — Listerial endocarditis, A39.51 — Meningococcal endocarditis, A52.03 — Syphilitic endocarditis, A52.06 — Other syphilitic heart involvement, A54.83 — Gonococcal heart infection, B33.21 — Viral endocarditis, B37.6 — Candidal endocarditis, I01.1 — Acute rheumatic endocarditis, I01.8 — Other acute rheumatic heart disease, I01.9 — Acute rheumatic heart disease, unspecified, I02.0 — Rheumatic chorea with heart involvement, I09.9 — Rheumatic heart disease, unspecified, I33.9 — Acute and subacute endocarditis, unspecified, I38 — Endocarditis, valve unspecified, I39 — Endocarditis and heart valve disorders in diseases classified elsewhere, M32.11 — Endocarditis in systemic lupus erythematosus

Same Index main term, other category

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

I08.3 — Combined rheumatic disorders of mitral, aortic and tricuspid valves (tricuspid, with, mitraldisease, aorticdisease), I08.8 — Other rheumatic multiple valve diseases (multiple valves, specified disorders), I08.9 — Rheumatic multiple valve disease, unspecified (multiple valves), I09.1 — Rheumatic diseases of endocardium, valve unspecified (rheumatic), I09.89 — Other specified rheumatic heart diseases (pulmonary, rheumatic), I25.3 — Aneurysm of heart (heart), I25.41 — Coronary artery aneurysm (coronary), I25.89 — Other forms of chronic ischemic heart disease (coronary, vein), I28.0 — Arteriovenous fistula of pulmonary vessels (arteriovenous, acquired, pulmonary), I28.1 — Aneurysm of pulmonary artery (lung), I34.89 — Other nonrheumatic mitral valve disorders (mitral), I35.8 — Other nonrheumatic aortic valve disorders (aortic), I36.8 — Other nonrheumatic tricuspid valve disorders (tricuspid, nonrheumatic), I37.8 — Other nonrheumatic pulmonary valve disorders (pulmonary), I38 — Endocarditis, valve unspecified, I42.3 — Endomyocardial (eosinophilic) disease (Löffler's), I60.0 — Nontraumatic subarachnoid hemorrhage from carotid siphon and bifurcation (carotid artery, ruptured into brain), I60.6 — Nontraumatic subarachnoid hemorrhage from other intracranial arteries (circle of Willis, ruptured), I60.7 — Nontraumatic subarachnoid hemorrhage from unspecified intracranial artery (berry, ruptured), I60.8 — Other nontraumatic subarachnoid hemorrhage (brain, meninges, ruptured), +304 more

Contextual Map

Every relationship of I33.0 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 I33.0 with these 5 related codes in Claim Check

Hierarchy

Use Additional Code

Index manifestation

Referenced by Code First instructions

Clinical classification (CCSR)

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. 15,708 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027
  • MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — 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.”— CMS MS-DRG Definitions Manual · FY2027

Index entries (31)

  • Aneurysm (anastomotic) (artery) (cirsoid) (diffuse) (false) (fusiform) (multiple) (saccular), endocardial, infective (any valve)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Aneurysm (anastomotic) (artery) (cirsoid) (diffuse) (false) (fusiform) (multiple) (saccular), infective, endocardial (any valve)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Aneurysm (anastomotic) (artery) (cirsoid) (diffuse) (false) (fusiform) (multiple) (saccular), mycotic, endocardial (any valve)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Arthropathy, in (due to), infective endocarditis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Arthropathy, reactive, in (due to), infective endocarditis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disorder (of), glomerular (in), subacute bacterial endocarditis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Endocarditis (chronic) (marantic) (nonbacterial) (thrombotic) (valvular), acute or subacute, infective[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Endocarditis (chronic) (marantic) (nonbacterial) (thrombotic) (valvular), bacterial (acute) (any valve) (subacute)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • and 23 more

Nearest codes

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 FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 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 — v44 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. "I33.0 — Acute and subacute infective endocarditis." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/i33.0-acute-and-subacute-infective-endocarditis

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Acute and subacute infective endocarditis

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, 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 I33.0 in its code family, with their registry titles.

View all codes in the I33 family