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I46.9 ICD-10-CM Code: Cardiac arrest, cause unspecified

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

Coding at a Glance

Tabular directives
1 Excludes2
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 84

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 296 — CARDIAC ARREST, UNEXPLAINED WITH MCC (MDC 05)
  • MS-DRG 297 — CARDIAC ARREST, UNEXPLAINED WITH CC (MDC 05)
  • MS-DRG 298 — CARDIAC ARREST, UNEXPLAINED 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)

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 213 — Cardio-Respiratory Failure and Shock

Other models: CMS-HCC V22 HCC 84

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 I46.9 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 I46.9 itself; “inherited from” names the category or block whose note applies here.

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from I46

Coder workflow for I46.9

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

Before you code I46.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, I46.9 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewI46.2, I46.8

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — I46.9 is appropriate when the documentation goes no further.

    ReviewI46.2, I46.8

Consider I46.9. Then 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).
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes2 — not part of I46.9(1 note)

    Coding workflow: The conditions named in this note are not included in I46.9. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareR57.0

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

Coding decision scenarios

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

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewI46.2, I46.8

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 I46.9 with…

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

The codes most likely to be picked instead of I46.9 — 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.

  • R57.0— 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 cardiogenic shock adds R57.0; it is not part of this code and both may be reported when both are documented.

    Full comparison: I46.9 vs R57.0 →

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

Cardiac arrest, cause unspecified is a billable ICD-10-CM diagnosis code (I46.9).

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 (1)

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; counts only for patients discharged alive.

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 I46.9 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 Excludes1 note: R09.2 — Respiratory arrest (via I46.-).

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

Referenced by 1 Excludes2 note: I50 — Heart failure (via I46.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

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 25 clinically related codes on its CMS exclusion list. Counts only for patients discharged alive; otherwise treated as a non-CC.

Named in the grouper logic of 5 MS-DRGs: DRG 296 (MDC 05), DRG 297 (MDC 05), DRG 298 (MDC 05), DRG 791 (MDC 15), DRG 793 (MDC 15).

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

Clinical classification (AHRQ CCSR):CIR018 — Cardiac arrest and ventricular fibrillation (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. Counts only for patients discharged alive. 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.

I27.841 — Fontan-associated lymphatic dysfunction, I27.848 — Other Fontan-associated condition, I27.849 — Fontan related circulation, unspecified, I47.0 — Re-entry ventricular arrhythmia, I47.10 — Supraventricular tachycardia, unspecified, I47.11 — Inappropriate sinus tachycardia, so stated, I47.19 — Other supraventricular tachycardia, I47.20 — Ventricular tachycardia, unspecified, I47.21 — Torsades de pointes, I47.22 — Catecholaminergic polymorphic ventricular tachycardia [CPVT], I47.29 — Other ventricular tachycardia, I47.9 — Paroxysmal tachycardia, unspecified, I48.0 — Paroxysmal atrial fibrillation, I48.3 — Typical atrial flutter, I48.4 — Atypical atrial flutter, I48.91 — Unspecified atrial fibrillation, I48.92 — Unspecified atrial flutter, I49.01 — Ventricular fibrillation, I49.02 — Ventricular flutter, I49.2 — Junctional premature depolarization, +4 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Cardio-Respiratory Failure and Shock) for risk-adjusted payment.

I46.2 — Cardiac arrest due to underlying cardiac condition, I46.8 — Cardiac arrest due to other underlying condition, I49.01 — Ventricular fibrillation, I49.02 — Ventricular flutter, J80 — Acute respiratory distress syndrome, J81.0 — Acute pulmonary edema, J96.00 — Acute respiratory failure, unspecified whether with hypoxia or hypercapnia, J96.01 — Acute respiratory failure with hypoxia, J96.02 — Acute respiratory failure with hypercapnia, J96.10 — Chronic respiratory failure, unspecified whether with hypoxia or hypercapnia, J96.11 — Chronic respiratory failure with hypoxia, J96.12 — Chronic respiratory failure with hypercapnia, J96.20 — Acute and chronic respiratory failure, unspecified whether with hypoxia or hypercapnia, J96.21 — Acute and chronic respiratory failure with hypoxia, J96.22 — Acute and chronic respiratory failure with hypercapnia, J96.90 — Respiratory failure, unspecified, unspecified whether with hypoxia or hypercapnia, J96.91 — Respiratory failure, unspecified with hypoxia, J96.92 — Respiratory failure, unspecified with hypercapnia, P22.0 — Respiratory distress syndrome of newborn, P26.0 — Tracheobronchial hemorrhage originating in the perinatal period, +15 more

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.

Respirator Dependence/Tracheostomy Status/Complications, Respiratory Arrest

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Cardiac arrest and ventricular fibrillation).

I46.2 — Cardiac arrest due to underlying cardiac condition, I46.8 — Cardiac arrest due to other underlying condition, I49.01 — Ventricular fibrillation, I49.02 — Ventricular flutter, I97.120 — Postprocedural cardiac arrest following cardiac surgery, I97.121 — Postprocedural cardiac arrest following other surgery, I97.710 — Intraoperative cardiac arrest during cardiac surgery, I97.711 — Intraoperative cardiac arrest during other surgery, O03.36 — Cardiac arrest following incomplete spontaneous abortion, O03.86 — Cardiac arrest following complete or unspecified spontaneous abortion, O04.86 — Cardiac arrest following (induced) termination of pregnancy, O07.36 — Cardiac arrest following failed attempted termination of pregnancy, O08.81 — Cardiac arrest following an ectopic and molar pregnancy, O29.111 — Cardiac arrest due to anesthesia during pregnancy, first trimester, O29.112 — Cardiac arrest due to anesthesia during pregnancy, second trimester, O29.113 — Cardiac arrest due to anesthesia during pregnancy, third trimester, O29.119 — Cardiac arrest due to anesthesia during pregnancy, unspecified trimester

Same Index main term, other category

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

I45.5 — Other specified heart block (sinus), I97.12 — Postprocedural cardiac arrest (cardiac, postprocedural), I97.71 — Intraoperative cardiac arrest (cardiac, intraoperative), M89.12 — Physeal arrest, humerus (epiphyseal, partial, humerus), M89.13 — Physeal arrest, forearm (epiphyseal, forearm), M89.15 — Physeal arrest, femur (epiphyseal, partial, femur), M89.16 — Physeal arrest, lower leg (epiphyseal, lower leg), M89.168 — Other physeal arrest of lower leg (epiphyseal, lower leg, specified NEC), M89.18 — Physeal arrest, other site (epiphyseal, specified NEC), O29.11 — Cardiac arrest due to anesthesia during pregnancy (cardiac, complicating, anesthesiaor other sedation, in pregnancy), O64.0 — Obstructed labor due to incomplete rotation of fetal head (transverse), O74.2 — Cardiac complications of anesthesia during labor and delivery (cardiac, complicating, anesthesiaor other sedation, in labor and delivery), O75.4 — Other complications of obstetric surgery and procedures (cardiac, complicating, delivery), O89.1 — Cardiac complications of anesthesia during the puerperium (cardiac, complicating, anesthesiaor other sedation, postpartum, puerperal), P28.81 — Respiratory arrest of newborn (respiratory, newborn), P29.81 — Cardiac arrest of newborn (cardiac, newborn), Q32.1 — Other congenital malformations of trachea (development or growth, tracheal rings), R09.2 — Respiratory arrest (respiratory), R62.50 — Unspecified lack of expected normal physiological development in childhood (development or growth, child), Z65.3 — Problems related to other legal circumstances (legal, anxiety concerning), +1 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Iron Panel, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of I46.9 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 I46.9 with these 2 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

  • R09.2 — Respiratory arrest[Excludes1](via I46.-): “cardiac arrest (I46.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes2 notes

  • I50 — Heart failure[Excludes2](via I46.-): “cardiac arrest (I46.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 213 — Cardio-Respiratory Failure and Shock [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. 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

  • Arrest, arrested, cardiac[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

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
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. "I46.9 — Cardiac arrest, cause unspecified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/i46.9-cardiac-arrest-cause-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Cardiac arrest, cause unspecified

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 I46.9 in its code family, with their registry titles.

View all codes in the I46 family